ToME: the Tales of Maj'Eyal

I unlocked the archmage class and was thinking they would have some super powerful spells but be really easy to kill. The latter part seems to hold true but I must say i'm disappointed with their spells. they all seem to cap out at around 200 damage or so.

I'm still low level on this character so maybe im missing something

I just finished my shadowblade char which i loved, ton of unique skills and high damage capability.

With lower level fighters doing that in a single hit I guess i just feel like i'm missing something with this class

any recommendations on what makes them such a powerful casting class?

There are 4 unlockable categories which you are likely missing.
Also, all the damage talents scale with Spellpower. Increase that and you do more damage.

Archmages really aren't about being the sort of 'glass cannons' you might expect from other games. They are well rounded in their wizardry which can offer a great mix of strategies in many different and distinct ways. As opposed to a Shadowblade where the focus is simply about inflicting damage and making use of talents to allow you to inflict more damage, the Archmage needs to use a mix of defensive abilities and enemy control talents to hold off enemies while wearing them down with their array of spells.

Yeah, the squishy wizard trope really just does not apply to ToME. Archmages are one of the tankiest classes out there, about two or three times more survivable than Bulwarks, the stereotypical sword and shield class. Plus they have access to a ton of utility, probably more than Shadowblades. Meanwhile, their damage starts out strong and sort of trails off lategame compared to some melee classes. That said, their spells don't "cap out" at 200. You can hit for 2000 damage or more with a single spell if you build your character right. It's just that there are classes that hit harder.

Mex has a great understanding of the class so I would direct you to his guide. It's technically tailored to Madness difficulty but everything he says can be successfully applied to Normal difficulty as well.