Is it a valid Christian concept to attribute subjectively attactive physical characteristics, as blessings from God?

In some circumstances in every culture it may be a curse. It can of course be a blessing too. I would say that most of the time it is neither, being a benign state of being, like being male or female.

This we know for sure:

13 For you created my inmost being;
     you knit me together in my mother’s womb.
14 I praise you because I am fearfully and wonderfully made;
     your works are wonderful,
     I know that full well. Psalm 139

We all "are fearfully and wonderfully made" and God himself "knit [us all] in [our mothers'] womb." The look and state of our bodies is clearly God's desire for His purposes. It is, therefore, good, making it neither blessing nor curse unless within specific context.

I suppose this leaves the question for deformities open. I don't really know how to answer that except with more of them same (God's purposes) and that sin has corrupted our bodies.

Short Answer: Biblically speaking, absolutely not.

First, let me clarify that I do think a case could be made that disfigurement is the result of sin. For example, if a person were covered in warts, or scars, or had a cleft lip, or was missing an eye, or was obese, or malnourished, I think it would be safe to say that person had experienced the effects of sin.

However, beyond this, ranking people's relative "attractiveness" tends to be a practice characteristic of the "world" -- not God or His people. There are zero examples in Scripture of God "blessing" someone with "greater attractiveness" than another person. (Except, of course, in the eye of their spouse.) Remember:

God sees not as man sees, for man looks at the outward appearance, but the Lord looks at the heart. -1 Samuel 16:7

Sheesh, even Jesus, the Perfect Man, is described as... well... "nothing special to the eyes" so to speak:

He has no stately form or majesty that we should look upon Him, nor appearance that we should be attracted to Him. -Isaiah 53:2

The blessings from God upon His people are not fleshly "attractiveness" relative to others... God's blessings are life, peace, joy... abundance in the Spirit. Do a quick search on "blessings" in the New Testament and this will be clear.

God's instructions to His people throughout Scripture run in the opposite direction to the world's fascination with ranking people's "attractiveness":

Do not judge according to appearance, but judge with righteous judgment. -John 7:24

And again...

Do not love the world nor the things in the world. If anyone loves the world, the love of the Father is not in him. For all that is in the world, the lust of the flesh and the lust of the eyes and the boastful pride of life, is not from the Father, but is from the world. The world is passing away, and also its lusts; but the one who does the will of God lives forever. -1 John 2:15-17

And remember the words of the wise man:

Charm is deceitful and beauty is vain,
But a woman who fears the Lord, she shall be praised. -Proverbs 31:30

We are not called in Scripture to rate people by the appearance of their flesh. We are called to place value on devotion to the Lord, cherish our spouses, and pursue things that matter.

My Dad used to have some words hung on the wall in his office that said, "I'm me, I'm wonderful, 'cause God don't make junk."

I say that because I think this is what it's all about. Neither my Dad (nor I for that matter) are particularly attractive men. We're both stocky and somewhat short. That being said, I could consider my build to be a curse, or I could consider it to be a blessing no more or less than your friend's beauty, because it's the way that God made me, and he had a very specific reason he made me like that. We are to use our strengths and weaknesses for the purposes of doing the good God lays out for us to do.

The book of Esther is a great example. In it, Esther uses her beauty as a tool to preserve the entire nation of Israel. The focus of the story isn't the fact that she had beauty, it was how she used it for the good of Israel, by using her position, gained by her beauty, to stop a plot that would have wiped out the nation. Her beauty saved lives.

The moral of the story is this: while your friend may be blessed with beauty, it's not about having the blessing as much as it is about using the blessing.

Every person is fearfully and wonderfully made (Psalm 139:14), and if they are a Christian, then they are God's workmanship, created in Christ Jesus to do good works which God has laid out beforehand (Ephesians 2:10). Nobody else is as qualified to do the good works God lays out, as much as the person for whom they're laid out. This means we're all custom built, and there are no mistakes in the way that God makes us regardless of whether we have beauty or not. Our very being is a blessing, and being beautiful is no more or less a blessing than not being beautiful.

I'd encourage your friend to look for ways she can use her beauty for God's greater purpose, and to not focus on it as a good in and of itself. Beauty, just like any culturally attribute, is a tool, and, depending on how it is used, can be either a blessing or a curse.

Physical beauty is not ultimately subjective. Our notions of physical beauty are often tainted and perverted by sin, but they're ultimately and objectively based on health and procreative power. Numerous studies confirm this: http://en.wikipedia.org/wiki/Physical_attractiveness.

And, particularly in Catholicism, procreative power and the act of procreation is both good and integral to marriage.

“The matrimonial covenant, by which a man and a woman establish between themselves a partnership of the whole of life, is by its nature ordered toward the good of the spouses and the procreation and education of offspring; this covenant between baptized persons has been raised by Christ the Lord to the dignity of a sacrament.” (Catechism of the Catholic Church, paragraph 1601)

And, among copious other affirmations that marriage and procreation are highly good,

Called to give life, spouses share in the creative power and fatherhood of God. “Married couples should regard it as their proper mission to transmit human life and to educate their children; they should realize that they are thereby cooperating with the love of God the Creator and are, in a certain sense, its interpreters. They will fulfill this duty with a sense of human and Christian responsibility.” (CCC 2367)

And this is supported numerous places in the Bible as well, but most obviously in the beginning. It's the very first command and blessing given to humans.

²⁷ God created mankind in his image; in the image of God he created them; male and female he created them. ²⁸ God blessed them and God said to them: Be fertile and multiply; fill the earth and subdue it. Have dominion over the fish of the sea, the birds of the air, and all the living things that crawl on the earth (Genesis 1:27-28)

Here, God's first command, to be fertile and multiply, is given in the context of a blessing. And we know that beauty, however tainted our perception and treatment of it may be, is ultimately a sign of procreative power. So, right off the bat, beauty is good and arguably a blessing.

To be clear, a blessing is something which affirms or assists us in a holy or divine purpose (What does it mean to "Bless the Lord"). Beauty is an assistive recognition of our divine purpose, our first-received command, to procreate. And it is, in that respect [among others], a blessing.

As noted though, our perceptions and values are tainted by sin. We tend to hyperfocus on it, sifting it out as its own thing, rather than a single component of the mystery of creation, making an idol of it, and holding tainted, pleasure-serving perceptions of it. And for that reason, we must be careful not to hastily attribute all "beauty" to God's blessing, nor to be envious of any blessing.

All things are given by God. God gives to whom He desires. And Christ blatantly suggests at numerous times, often through parables, that our blessings are unequally distributed. The parable of the talents is a good example of this.

Like the Angels, we do well to recognize and co-bless, but not covet, those who have been blessed by God:

²⁶ In the sixth month, the angel Gabriel was sent from God to a town of Galilee called Nazareth, ²⁷ to a virgin betrothed to a man named Joseph, of the house of David, and the virgin’s name was Mary. ²⁸ And coming to her, he said, “Hail, favored one! The Lord is with you.” (Luke 1:26-27)

Beauty is in the eye of the beholder, what someone finds beautiful, another finds ugly. If they can use their beauty to help others it could even be a gift. I think of Queen Esther in these regards, she was blessed with beauty and that gave her the opportunity to become a queen. She used what she had (beauty) to become a queen. And she had courage enough to stand up for her people so she even had inner strength.

But of course, disfigurement can also be a gift as well, it can be very inspiring to see how determined some people are to do what they love. While they may not go out and talk about God, just by doing what they are doing it show God to others. And like I said before, beauty is in the eye of the beholder, this guy with no arms or legs is so adorable! Check out the second link.

True Story of Not Giving Up

No Arms, No Legs, No Worries!

Yes, it is completely valid to attribute any blessing to God from a variety of Christian perspectives. In short, all things are ordained by God.

As for the "less attractive" person, God has most likely blessed her with other attributes.

And if not, a perfectly Christian answer to why some are blessed with certain things and other are not is the one God gave to Job... "Where were you when I laid the foundations of the earth?". In other words, who are we to question God? Rather, according to most Christian teachings, we should thank God for what we have, realize that all blessings come from Him, and not complain about what we didn't get.