I'm trying to create new spell, which requires both hands to cast (Guardian Circle style). I set BothHands casting, and it's equipped to both hands in game, but casting animation is still for one, left hand. How can I change this animation?

did u make sure in the CK that its duelwieldable?

Dual-wieldable not, two-handed yes. Equip type is set to BothHands. Do not mistake this with dual casting.

Its just a theory, but going through the spell listings in the CK I notice that every Master-level spell is marked with a "RitualSpellEffect" keyword tag (look at the effect under "magic effect" and not the spell). It could perhaps be related to that, perhaps that keyword tells the game to use the fancy 2-H cast animation.

Another possibility would be the Casting Art (also in the effect entry). All the master spells have unique Casting Art entries as well. Could be the casting art determines which animation is used.

I used both ways just to make sure, and it worked. Thanks