once promoted, if you choose to stay down the path of your current class and not combine with another class, you will get access to a promotion relic weapon; this weapon will not deal as much damage as the highest weapon you
have access to at that level, but it will have some form of passive effect that makes it worth the trade-off...
the weapon in the game right now are...
Axe of Storms - Knight-Captain weapon that will unleash a storm of lightning bolts at all hostiles in the area if all attacks land on the same target
Staff of Sorcery - Great Magus weapon that gives all single-target combat spells a 10% chance to deal critical damage which is a percentage based on your combined intellect and knowledge.
Maul of Healing - Celestial Priest weapon that heals the wielder for 50% of any single-target healing spell cast on someone else and also gives area-effect healing spells a 10% chance to deal a critical healing effect which is a percentage based on current knowledge.
Dagger of Quickness - Assassin weapon that gives the wielder a bonus attack per round
Spear of Vampirism - Pathfinder weapon that marks any target it hits allowing any tamed creature under the wielder's control to heal for a portion of any attack damage
Flail of Regeneration - enhances the wielders fadi spell to heal for 3x the normal amount and also gives the fadi spell a new dynamic as it can be cast as an area-effect spell which will heal all group members for a small amount that will tick every 5 seconds for the next 30 seconds.
Bow of Aetherwind - allows the firing of special arrows which forgo normal damage in lieu of magical-based
effects based on the arrow fired which will be consumed upon use
Staff of Sanctis-Mortem - empowers any risen undead under the wielders control and they will now heal based off damage dealt by the staff and any attacks they deal will always ignore the target's armor
To acquire these weapons, you seek out the Duergar Fortress which you must be promoted to enter, and once there you find a duergar enemy that matches your class... defeat it and you get a 10% chance to receive it.
good luck!