First, THF40/NIN20.
Compared to that stupid Skeleton, this guy was NOTHING.
Went in by myself... Cast Utsusemi [Again, since it stripped me], and engaged. Much more accurate than I expected, but the fight switched to the cutscene just as he was about to maybe hit me once. He had about 75% health at the time... Definitely not halfway.
NPC came in, provoked it, and I stayed behind the enemy until my SA timer kicked in. Finished it off shortly after hitting it with a SA+Viper Bite.
Certainly didn't do it fast, but I was never in any danger with this fight.