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).