Playing on PC with an Xbox 360 controller. When holding the right trigger(heavy attack), pressing the left trigger causes the heavy attack to happen.

Example: Highlander offensive stance and Shinobi ranged heavy both require holding the heavy attack button (in this case right trigger). Pressing left trigger while right trigger is held down causes both characters to perform their respective attacks.

This becomes an issue when left trigger is rebound to actions like guard break or feint, as this behavior makes any character with a heavy attack hold mechanic have great difficulty cancelling their move, or it causes difficulties when wanting to perform moves like highlander kick or shinobi ranged guard break.

I should mention that while you can technically cancel highlander offensive stance/ shinobi ranged heavy without executing the attack in this situation, It requires the player to release the right trigger and then immediately press the left trigger bound to feint. The timing window is very slim