Fragsie,
I like the first image you showed because he's more "stocky", so please use that one. Here are some ideas I have for his equipment (if you can).
Armor: Just make this a thick "band" of fur (supposed to be griffin hide) that crosses from his right shoulder to his left hip. Also, if you can, have
the attached dragonmark image poking out and mostly visible from under the band of fur over his heart (shrink to scale as needed).
Cloak: A cloak of scaled feathers. I'll give you all the creative license you'd like on this one, but I figure that this would be griffin feathers (golden-brown?)
Sword: a longsword, it's cross guard carved to resemble a series of dark clouds and its blade etched with the design of a lightning bolt striking the very same mountain he stood upon. (Not sure if you can do this, but it would rock if you could!)
Gauntlets: Dark metal gauntlets. Nothing special unless you want to put some kind of faint aura of "force" around them.
Shield: This is a basic large shield. Have fun with this one, as I don't really have in mind anything specific.
Markings: Instead of the normal markings (random patterns of splotches) found on Goliaths, Kortauhk has dark lines of "lightning" running all over his skin. I would prefer a more "natural" lightning look rather than the stylized jagged lightning bolt symbol.
Thanks Fragsie! Can't wait to see how it looks!