My idea is combat debuffs. say you are in combat or you are hunting and you hit someone with a rock.there should be a chance to get blunt trauma which gives you a concussion or something. Maybe being hit my an arrow or being gored by a boar or bitten by a bear will cause bleeding.bleeding should cause you to lose small to large amounts of health at a time depending on wound size.This will make first aid more useful.Debuffs will also make combat more complex and difficult
Debuff ideas
Being hit by blunt object such as rock or fist: Chance to cause trauma which will make attacks less accurant and movements slower.
Being hit by sharp object such as arrow,sword or teeth: chance to cause bleeding which will cause HHP or SHP lose over a period of time.
Intimidated by your enemy's superior strength or party size:causes attacks to be weaker and less accurant.
this is all i can think of now so if you like this idea you should add it to the game. Please try to think of more debuffs in comment section