The 4e mechanics in your link seem off. Is Arthur meant to be a PC or an NPC? At one point, you label him a "Warlord," which is a PC class. But he's stat-ed as a monster (a level 21 leader). As mentioned before in this thread, NPCs and PCs use different stats in 4e. Also, as a standard monster, he has too many attacks, with an at-will multi-attack, a immediate interrupt triggered attack when he's hit (which should probably be an immediate reaction), and a close blast encounter power which inflicts blindness (save ends). Also, you have two recharge powers, but don't state what numbers they recharge on.
I would suggest looking at the stat-ed up version of Drizzt Do'Urden from dragon magazine (or was it Dungeon?) about a year ago. It should be in the character builder. That would probably give you a good guideline for building high level NPC solos out of popular fictional characters. If you look at the Dark Sun Creature Catalog, they have stat-ed out a number of prominent Dark Sun NPCs (mostly the Sorcerer-Kings) and that can also be useful to you.
