Here are a bunch of my ideas, some are more difficult to implement than others.
Hammer requires two arms-
Make the player unable to use the hammer if they are missing one arm, it is op and needs a nerf
You should be able to use your sword one handed no matter which hand it is. It is extremely annoying to lose one voxel off your right arm and die.
One handed animations-
Once you lose one arm, the sword swing animation should be slightly tweaked, but the swing path should remain the same. Right now the player moves both shoulders when they swing even if they only have one arm.
Sword length upgrades-
There's should be upgrades that increase the length of the sword and thereby its range. Even now I feel the sword length is a little too short and I often miss targets because I am not close enough.
Buff one legged movement- one legged movement should be fast enough to be useable, and not a completely debilitating injury.
Change melee AI- the sword and hammer bots should charge forward towards you, attack, and then fall back a little bit, and charge again while steadily moving away from others to try to flank you instead of circling around you and clustering together.
Tilt sword when moving
When moving left and right, your sword should tilt 45 degrees the opposite way. This would make blocking easier as it automatically move so the sword to a location more optimal for blocking when trying to side strafe an attack.
Automatically tilted swings-
The vertical swing is extremely tedious to use. I find myself constantlymissing archers in close quarters when I am unable to use a sideways swing. Your sword should tilt by 15-25 degrees towards the closest enemy to make using the vertical attack easier.
Sideways swings go in the same direction as your movement-
The current directional swings feel backwards to me. When you move in a direction and attack, the swing should be in the same direction, not the opposite.