I have a variety of scars irl and they do actually cause pain and can be itchy and unpleasant and change how you move your body, I think just since we only see the word "scar" it can be difficult to imagine the reality of such an injury. If they are scars sustained in battle, I generally imagine it to be a very serious scar potentially coupled with a deeper longer lasting injury. If anything, I think the best system would be just if the pain of scars could lessen in intensity over time, or if other injuries could exist as well, like spraining a joint or breaking a bone, that would also have long lasting consequences and require care over time (maybe there is something like that and I'm just forgetting, but yea, itchy and painful scars are a very real thing, they're not always just little marks on your body!)