It really depends on what your doing, & who your fighting. One of the basic for PvP is your going to need resist, heal, & damage your opponent.
If your looking at being a melee person Weapon, Tactic, & Resist or must have skills. Its up to you to fill in the rest on your warrior. There are a wide range of other skills you can add; Necromancy, Spirit Speak, Mysticism, Focus, Chivalry, Bushido, Magery, Eval, Parry, Poison, Ninjutsu & Medation to name a few.
Potions, Enchanted Applies, & trapped pouches may be a few goodies you might want to carry.
If your fighting a melee type DCI, HCI, HLD, & HLA can be important. If you fight mages you want to be able to hit fast. Weapon specials are another thing to consider.