When a knight is backed against a wall, firing the Mandolin (and possibly the Slicers, I cannot check) will cause 1 out of 2 projectiles to impact against whatever is behind you. This can sabotage your damage output as you will lose some of the projectiles this way.

The issue can be easily observed by placing your back against a breakable stone block, or an explosive cube. When you fire the Mandolin facing away from the object, it will still damage the object.
This has led to some confusing moments where explosive cubes have been set off and injured me by mistake.

I had wanted to check if such an issue had already been reported with discguns before, but when I attempt to use the forum’s search feature, I am told I don’t have permission to access this resource.