I´m trying to do the the same thing in my project, and right now I´m using three different collision boxes.
Box one is the one I pin (using PIN-behavior) the character sprite to. This box handles the player movement.
Box two, somewhat smaller than box one, is pinned (using PIN-behavior) to box one. I use this box to check if the player gets hit. (I made it a little smaller so the player doesn´t feel he gets hit unfairly)
Box three is a rectangular box that I put on an image point I have on the sword´s edge. I don´t use PIN-behavior here (since you can´t PIN things to specific image points), but rather use: Every tick->set position to another object.
I use box three to check if the sword hits the enemies.
So far it seems to work ok, but I´ve just recently started this project, so we´ll see.
I´m sure there are a lot of (probably better) ways to do this though.