The setting is a homebrew fantasy world country with technology roughly on the level of early 1800s England. There is magic that innately boosts the immune system, metabolism, and general body functions of every single person in the world, and can be used for spellwork by anyone with the time and money for intensive training (which, admittedly, is not a whole lot of people). There is not magitech or significant healing magic.
My hero Urde is in his late teens now and attending a sort of military school for magic users. (This is a fantasy but let's call it post-Renaissance. I've even given them indoor plumbing, as well as magic-powered lighting) Several years ago, Urde's father, Lord Graves (a respected military hero) was caught in one of his rages and hit Urde on the head with a vase -- probably on the temple because it was bad enough to temporarily kill Urde. His father brought him to the healer right away, and Urde was revived, but of course he had a lot of emotional and psychological issues.
Urde mentioned that it left a scar -- not just the physical one. I've written about his internal scars (phew have I ever), but I realized I don't know what the external scar would look like. Or if they would be visible. Or if this injury would have to leave a scar. Also, Urde's hair is quite long, so it might hide the scar. Maybe that's why he started growing his hair long -- although I prefer to think he grew his hair long out of rebellion. (Also, this society has powerful healers, so a really bad scar could be healed, but the healers are simply accelerating the natural healing process, not replacing it.)
It's a good thing my original submission was lost in the ether because,I forgot to mention the initial research I did. I first Googled using "hit on head" and scar and didn't find too much. I used the advice in your article on search tips, then tried "struck on head" and scar and found some more information. (Including autopsy photos. Whoops.) I also read previous posts about head injury from your site, and saved some of them. I also posted similar questions on the writing sites AbsoluteWrite and FMwriters (and have received a few responses on both boards).