Let's have a look at this (and my knowledge of attacks and defences is far from complete, so feel free to add to this)

Knights have jj. Defences: Fullparry, malloran, alkar, aloofness, bladebar, high defence in relation to attackers swordplay, pentacle, nabbing swords

Sorcerors have blackhand and demons. Defences:

Hold breath, pentacle, alkar, various demon-dispelling skills

Mages have rits. Defences:

Counter potions, runes and herbs, various anti-rit guild skills (mysteriously missing from any knight skillset)

Seers have bonding and curses. Defences:

Herbs and potion cures, mind barriers, runes

Thieves have stabbing, yanking and throttling amongst others. Defences:

Hold breath, pent, malloran

Bards have songs and drams. Defences:

Deafness and blindness

Loremaster types have potion splashing and staves as well as lore-stave arc

Umm...

Er.....

It'll come to me in a minute...

Oh yes, knights, warriors and cavs get visor for staves.

Aias (will pay 10k for anyone to suggest workable def for potion splashing, not including alkar or spirit cocoon or any animist skill)

Written by my hand on the 11th of Midsummer, in the year 1020.