Currently in the game, you can carry all three weapons (sword, bow, and hammer) but on a small robot that seems unrealistic. A couple of changes that can be made is to...
1. Make a weapon capacity limit. You can only carry two weapons onto the battlefield. (If you want to take hammer and bow then there could be a weapon storage on the right wall of the "armory/upgrade" room that allows you to switch out which weapons you take into battle)
2. When switching weapons create a delay (possibly through an animation, ex. reaching onto the back to grab a sword/ bow/ hammer) that will prevent the switch from a hammer killing an enemy, to instantly switching and deflecting an arrow, to then shooting that archer with an arrow, then deflecting an arrow again.
Enemy Ideas:
1. A mimic/ mirror. If you have ever played Binding of Issac and gotten far enough, you will encounter an enemy that reflects your moves, but only has basic stats. So you could potentially make a robot that will mirror/ copy your moves (you walk forward, it walks forward. You walk and turn left, It walks and turns left)
2. Assassin. An enemy that is invisible until it gets close enough to you which then it will uncloak. You can have an introduction level to them by having commentatron and analysisbot talk about them and when the player gets to the level, its empty until they realize or die about/to the assassin bot.