Warden's pet is not like it used to be (below version 7.0). Now it is used to restore mana and health*, while its damage is low (except for the ability to tears - King of the Beasts).
It doesn't hold aggro but grabs your opponent's attention to your attack. Pets of other classes (summoner, psionicist, engineer, demonologist) also inflict dmg and provide additional bonuses for a given class.
* Scavenger (2% heal every pet attack); Life Balance (additional hp source for sharing).
When leveling, it's best to use equipment containing bloodlust (you heal by % damage dealt). Proficiency increases base damage. With determination, an additional orange bar appears under the life and mana bar. Its fulfilment during the fight determines the dmg increase by %. Brutality increases dmg by % depending on the health lost by the target. As you travel around Dane/Ammer, a new eq will appear that already has proper stat points (crit damage, double attack, shiftness, etc.).
Build and rotation are presented, among others, by Dragagon
here. When you have the right rubies, using one skill increases damage and reduces the casting time of another. In the case of pure dps (aspect of assault), with most activities (lvl, KoE etc.), you fight in range, but to inflict large dmg you use 1 skill in melee (Poisoned Thorn - ~ 25% of the whole dmg).