I think his biggest issue is there's too much emphasis on him being a lifesteal tank. His kit was archaic even at the time, but there's nothing inherently wrong with it other than clashing with his theme (he's an inspiring arbiter of battle, but doesn't show this through his gameplay).
Personally, I would shift away some of his lifesteal to raw defense stats and give him some more natural sustainability instead of having to force himself to work through the pain. I would probably also have him gain Blood Well stacks off of the spoils of battle rather than dealing damage to himself like an angsty teen. His whole status as an arbiter of battle should allow him to inspire other allies to fight harder, not unlike Jarvan's banner, but perhaps like Old Taric's ult.