I do like the idea of sheathes for your weapons, but the dual wielding idea would kind of break the game considering that all weapons (minus hammer) slice directly through your opponents, and I think it'd be an awkward situation for both the creators and the player if they did "lower damage"
When I picture lower damage in this game I think of the blade not going all the way through your enemy, but due to the fact that the weapons (except hammer) are pretty much lightsabers slicing through everything with ease, it'd make no sense in the terms of lower damage, where in this game is dealing with damage in percentage of body hit (+fire) instead of a health bar.
The sheathes I would like to see. The disappearing of your weapons is an odd thing (EXCEPT FOR NANOMACHINES SON)! It would be a cool little detail to add to the weapons. The sword having a sheath where the blade sticks out to damage your enemies is a possible idea, or just have a full cover for it, made out of the material that the floor and walls are made of, considering you don't disintegrate those on contact.
The bow could go on your back with a small hook or latch to keep it in place, and the hammer would be tougher, considering the upgrades making the thing HUGE. However, the huge hammer could grind on the ground with sparks cuz physics. With physics in mind, the sheathed weapons could sway in accordance to movement, ex) Sword goes upwards slightly if falling, to the sides when you strafe etc.
Thanks for reading! Keep up the good ideas and work guys!