Upvote:7
Well, if it was found in Constantinople being venerated as a relic of the Holy Blood, that would have been quite good enough. The events of Christ's life and the legends surrounding it were very immediate and personal for many Crusaders, and there was an expectation that traces of them would be found.
If it was presented by Baldwin III of Jerusalem, that would again have been more than good enough. He was King of Jerusalem. If anyone would have such relics, he would, and there was an expectation that these things would exist.
Yes, these beliefs could be exploited by the unscrupulous. There are beliefs that can be exploited at any time in history. It's a human characteristic.