Good to hear about the fixes.
As for the control scheme I would use WASD for movement, Mouse 1 for attack with knight, Mouse 2 to block, Mouse 2 to aim with witch and Mouse1 to fire. Space to interact. You could use the wheel to select items for example.
If you want to make it keyboard only I would go with. WASD for movement, Q for switching, F to disable/enable following, LShift for blocking, Space to attack/aim. E to interact.For the witches aiming I recommend removing the up and down arrow functionality and make it aim with only A and D. You could use the arrow keys to change items.
An alternative to that is Arrows for movement. Z to attack/aim, X to block, C to switch and F to disable/enable following and Space to interact.
Hope this was of some help. Keep on devvin. I'll be keeping an eye on this project for sure.