Question: Can a creature use spiked armor (PH 116 and 121 and cf. armor spikes on PH 123, 124) that is 1 or 2 size categories inappropriately sized (PH 113) so that the creature employs the spiked armor as a 1-handed or 2-handed weapon for use with the feat Power Attack (PH 98)?
Followup Question: If yes, does the inappropriately sized spiked armor occupy the creature's limb or limbs because it's now a 1-handed or 2-handed weapon? That is, can that creature who makes a full attack with the inappropriately sized spiked armor also use its natural attacks that are typically arm-based (e.g. claw, slam) as secondary natural attacks (i.e. at a -5 penalty and half Str bonus as a bonus to damage) or a light or 1-handed weapon as an offhand attack, suffering the standard two-weapon fighting penalties?
Context (or, "Why would this ever be a thing?")
The monster responsible for this question is a warden archon (BE 163-4). They're anthropomorphic bears with an extremely tame selection of spell-like abilities, fair DR that's overcome by their most common foes, spell resistance that crumples against foes that matter, an aura of menace that's based specifically on their class levels, and... um... scent, I guess. They can teleport but can't fly. They wear heavy armor yet have Tumble as a class skill. They don't have Balance, Intimidate, or Use Magic Device as class skills. They have no listed ranged attacks. They are a sad, sad CR 8, and totally vrock chow.
...And according to random Internet research Lunia, the first layer of Dungeons and Dragons' Seven Mounting Heavens of Celestia, is divided into 196 provinces, each under the command of one of these bear dudes.
I have some non-LG high-op 15th-level PCs arriving shortly on Lunia, and they'll encounter these CR 8s as the first line of defense, and the 100-Acre Wood rejects are toast if the PCs engage. I'm okay with that, but I want there to be some hesitation if the PCs decide to take on a province-ruling warden archon. Advancing the warden archon's HD to maximum (so he's Huge and Str 38 and CR 16) is a good start, but short of slapping class levels onto one (which I'd like to avoid because, y'know, Lawful Good should be good enough), the only thing I could come up with was exploiting the ridiculous BAB... except the bear dudes rely on their claws, and they don't meet the prerequisites for the feat Rapidstrike (Dr 73). I then considered the feat Blood-spiked Charger (PH2 92-93... shame about the errata), which is normally as lame as the warden archons themselves but sucks less when used by a Huge grizzly-ball of Power Attack-fueled spikes...
...but spiked armor is a light weapon. That means he'd use the Blood-spiked Charger feat's spiked avalanche maneuver to inflict the same amount of damage with his spiked armor that he'd inflict if he just used a two-handed weapon and the feat Power Attack, a prerequisite for the Blood-spiked Charger feat (albeit without the attack penalty), and he'd be better off (as is almost anyone) with--deep sigh--the feat Shock Trooper (CW 112), which, frankly, I'm a little tired of.
But then I thought, "Hey, can I just make the armor spikes bigger?" And then I thought, "I have no idea how that works."