10. Rework Weapon Degradation
Weapon degradation has largely been a blight upon games. Notably, it's considered almost universally to be the one thing keeping The Legend of Zelda: Breath of the Wild from being an absolute masterpiece. While it does add to a game's "realism," it does subtract from the fun.
Dying Light also suffered from this. Players would find an incredible weapon capable of slaughtering hordes of zombies, only to stick it in their inventory and forget about it, forever to be used "later." This is because every single weapon in the game came with a preset number of fixes. Once those were used up, the weapon was a pile of scrap metal.
This also had the added downfall of discouraging players from modifying their weapons. Why spend all the materials and money needed to make an electric katana when it will become unusable in a few hours?
One fix is to combine systems from the previous game with something like Witcher 3. Weapons are still given a set number of fixes... in the field. However, weapons can be brought to an in-game specialist and have their fixes reset for a cost. (in-game currency, not microtransactions, don't get any ideas)
This would provide a helpful balance between creating something immersive while maintaining the fun of using, again, an electric freaking katana.