i recently played through the game with a party of 3 fighters and a bishop. very early on in the game (in the monastery) i had everyone become a thief for a level and built up everyone's stealth to 60-70 and then switched them back to their main classes. the armor class bonus of 6 or 7 proved very effective, especially for the bishop but also for the fighter who were in beserk mode permanently.

in equipping the fighters i favoured items that conferred magical resistances (helmets, armor, amulets, rings etc...) rather than simply those with the biggest numbers for damage or armor class. this approach combined with the protective bishop spells meant they rarely were turned insane or turncoated etc...

not a very subtle group but extremely effective. bulldozed my way through numerous battles that had proved quite tough in previous games.