short ice
First off one very simple thing I think could be implemented is like different types of grips (tape,sandpaper, rope) giving it more accuracy and more top damage.
Another idea I had could be different items that could be created with metals, glass, plastic etc. That could be added or removed from melee weapons to add damage.
Say you could smelt metal balls for smashing heads. Melt some broken glass into a plastic mould for bleeding damage.
Or a spike attachment on something to implement zombies with.
Then you could even make things that further improve durability like a stronger material to cover weak parts or braces etc. Or increase attack speed by removing heavy parts of an weapon replacing it with a lighter material.
Damage over time would also be really cool. Like a rag and some alcohol for fire damage.
Mixing some chemicals to dip somthing in for poison. And even the above mentioned ideas for bleeding damage.
Using blunt weapons to cripple limbs etc.
Just a few ideas.
formal knoll