... currently does nothing?
I was thinking this as I was playing yesterday (not sure why it never occured to me before now) but I think it could help improve the flow of the game if it actually did something.
My initial thoughts were that pressing LT/RMB should draw cutlass and go into block stance, allowing you to follow up with RT/LMB to attack.
I had also thought just pressing RT/LMB would use the last item equipped, but I am not entirely sure if that would always be benificial.
