ToME: the Tales of Maj'Eyal

If berserkers have archery and shield defence why Archmages can't have a tree that makes a staff-whacking archmage build a little more viable?

if you mean the arcane blade's category, that's enhancement.
enchantment, is a talent category, that is in an addon called "arcanum class pack"

either way, berserker has a few categories, that might have synergy with with shields, and a ranged option is always nice.

archmage... every single one of his spells (except for flame shock) already has a range 10, and absolutly NOTHING in the class have a synergy with a melee attack.
if you want a melee archmage, you go for arcane blade. that's literally what he is, a melee archmage.

I think Archmagi did have Enhancement a long, long time ago. Not sure why it was removed - I guess just because they have so many other trees and it's obviously not that useful?

Archmagi don't use Stamina, and they don't make melee attacks.

Enhancement would be a very poor fit for them.