Heh, tanker.
AC 34? That is not bad at all at level 6. So what, +2 Mountain Plate and a +2 Greatshield, ammie of natural armour +1, ring of protection +1, and dex +1?
That number can get even higher with LA races, there's a LA +1 race with +8 Natural Armour out there. Defending Armour and shield spikes is more of a high level trick, thanks to greater magic weapon not scaling well at low levels. He could conceivably be combat expertising, though, for more.
For characters who have a 'no, fuck you' like a sorcerer I had once who had bound spirits with readied actions to counter enemy attacks in various ways or high AC/attack negating characters (Sidestep + Robilar's Gambit, say), the best thing is pitting them against NPCs who are surprised by their defences and then start trying to find a way around them. So the high dex swordsage/swashbuckler goes miss/miss/miss against a knight character, backs off, and then comes in again with a trip/disarm/tumble past combo, using circle throw as he goes to toss the knight down some stairs. Or in a more anime style, a powerful npc trying a multitude of different attack forms and spells to break a high tier character's defences and being delighted as he finds that his opponent can handle each new type of attack.
Good fun is also a mirrormatch with these kinds of characters. For example, a armoured blahblahhonourblah knight meets a caricature of themselves (loud, overdramatized version of their own attitudes) with a similarly insane AC and they smash away at each other hilariously futilely. Bonus points if the caricature version uses some Taunt style ability the armoured tank uses on enemy monsters on the tank.
