Randomness and Fic Question

http://screens.midgar-rock.org/ac/index.php?dir=movie&tot=1744&img=1464&page=25 What's this? I was watching AC again and I noticed this mark Seph seems to have, right above the left strap. Is it a scar? It remained throughout the scene as he talked, so it didn't seem to be a shadow. Hmm, pre-Nibelheim fanfic opportunity? It looks like it could be from a sword.

And I'm working on chapter 3 of I Don't Feel Enough For You to Cry, which will be from KH Sephiroth's POV. He's caught between life and death, in some odd place of nothingness. I was considering having him battle himself, literally, but on the other hand, that scenario might be more interesting to save for FF7 Sephiroth in Twilight and Dawn. Thoughts? And if I save it for FF7 Seph, what should KH Seph's challenge be?