Upvote:2
You'll need to look at the airline you're travelling with, and identify their cabin luggage requirements. It's unlikely to be considered a weapon, but most airlines have luggage dimension requirements so that they can fit in overhead luggage or under the seat in front of you. Due to different configurations, each airline might have its own policy.
If you want to be absolutely certain, email the airline asking, so that you have a written confirmation before you board your flight.