I'll start this off by saying: don't pay attention to the attribute tab, direct your attention to the raw stats instead (such as attack, Dex and magic power).
Weapons have a funky way of working, as they don't serve you as direct damage amplifiers, as they filter your damage through "damage scaling". it has a simple formula, depending on the stat being scaled and whether it is the damage floor, or the damage ceiling.

Attack power/Strenght based weaponry scaling:
damage floor = Base Damage Floor + ( Attack Power * 0.128)
damage ceiling = Base Damage Ceiling + (Attack Power * 0.32)

Magic power/Mind based weaponry scaling:
Base Damage Floor + ( Magic Power * 0.128)
Base Damage Ceiling + (Magic Power * 0.32)

Dex power/Dexterity based weaponry scaling:
Base Damage Floor + ( Dex Power * 0.128)
Base Damage Ceiling + (Dex Power * 0.32)

(final results that end in decimals must be rounded down.)
(Remember that you can see base stats by looking at your weapon in the inventory)

Also, your weapons have a damage "cap" or "treshold" that makes you unable to deal greater damage if you reach it. you may find out that a weapon's damage cap has been reached if the damage numbers in the inventory are a glowing yellow. That means that you have too much damage for the weapon and it cannot deal greater damage than that. the only way to deal greater damage with capped weapons is with their charged attacks, which have a superior damage cap.

but hey, what about skills? do those have a damage cap as well?
Good news, the dev is so cool that he knew not to give them damage caps, as it would be dumb. if your damage is capped, the only way to deal greater damage is through the use of attack skills, which have uncapped damage, but are still subject to a lesser amount of scaling. it's minor, so you don't need details on such a thing.

Be weary that most of the information mentioned here comes from the official Atlyss Wiki, it's just explained my way. If you need more details in damage, check the wiki then. Hopefully, you'll know how to optimize your build with this knowledge. Remember: GET BETTER GEAR, DANGIT

- Solo WIng (A.K.A. Hammer Head)