It adds crit and weapon damage. Are you asking if the set also makes your enchantments stronger, i.e. an absorb magika glyph that would normally be 200 would be 300 with War Maiden? I don't think it does that. I could be wrong, but unless it says so in the description, I've never heard of that.
Now I'm really interested to see if this is the case
The 5 piece bonus adds 400 spell damage to your magic damage abilities. So I wondered if that applied to the magic damage part of the glyp, but now you've mentioned it I'd like to know if the return is increased too
Magicka enchants are a set amount aren't they? They scale on the quality of glyph and gear, not the damage modifiers. In that case, War Maiden buff wouldn't affect it.
War Maiden does not buff enchants, only way you can buff enchant damage is with Torugs Pact set, Infused weapon trait, and percent damage done sources like berserk, advanced species, amplitude, piercing cold, etc
Oh okay then, is that the same for element enchants and any sets that buff specific forms of element damage
Any set that says it gives Spell or Weapon damage will not affect enchants, but things that give a % increase to a damage type will increase enchant damage. So for example the Morag Tong set increases Poison enchants by 10%. (for anyone attacking the affected target, not just the set-wearer). Similarly a dragon knight with Engulfing flames can increase everyone’s fire damage enchants by 10%.
This extends to CP’s as well, and Master at Arms directly boosts your damaging enchants, as well as Elemental Expert or Mighty.
You can also increase enchant damage indirectlythrough various sets by increasing your Physical or Spell Penetration and your Weapon or Spell Critical Chance or Critical Damage.
Edit: I believe minor Berserk (Slimecraw set) and Major/minor Slayer (trials sets) also increase enchant damage.