Could this be added during fights.

However.

Through weapons.

Through stealth enabled masks maybe! Which lower accuracy do to not seeing through them well.  But this definitely something that makes things fun.

I'd love to have some sort of stealth system but I'd like it to be it's own system rather than just being a small chance of each attack. I like your idea for some sort of mask.

Will add it to the list

An additional idea I had is in order to actually equip the mask you have to remove your armour. This makes it riskier to actually stealth attack people.