3 traits that could be easy to implement?
Being allowed to wield 2 items of relative size. Example; nothing that requires two hands. So a pistol and a blade. Maybe a weapon and a tool?
The Primary hand and the Off hand would have relative debuffing in function. So if you hold a pistol and anything else, your aim would be decreased a little and same with the off hand weapon. Simply holding a tool or small random object would only lower the weapon function accurately not using, a hammer for example.
How this would work practically? Shooting if using a firearm for distance works normally(plus the accuracy debuff). Where as the off hand weapon/tool would be automatically used for melee attacks/defense.
I happen to be ambidextrous in real life and I can write with both hands and do pretty much most things with both hands. My left being a little less so than my right. Should be noted that you will NOT be able to reload a firearm while dual wielding anything. The option to drop the off hand item should be set up though. Be it, into a holster, ground or into the inventory.
While you sleep you snore and as such you make noise during sleep which may attract mobs to you. There can be a mutation called Heavy Snoring which just increases the volume of it.
Clearly used as a debuff because you do not want to be eaten while you sleep.
3-Mutation called Owl/Velvet Skin:
Tiny whiskers cloistered together (like an owl has or like tight velvet) dampen vibration and wind, thereby making you slightly warmer. Slightly less noisy if you just happen to be completely naked, except for socks or a belt etc…ahem, anyway. The rub is that you will be slightly more absorbent to water. This is bad. (warmer but less happy when wet). Barks skin or whatever that buff is called cancels this mutations debuff towards water and as such allows the slight warmth buff to work its magic =D