Wish I'd seen this thread earlier. Assuming you were trying to do what I think you were trying to do, I've been doing it for months. Just using simple movs.
Picture in spoiler.
Here's a list of the movs I've been using for each weapon type.
Bow: COSTUME_BOW_READY
Claws: COSTUME_CLAWS_ZOOMED
Katana: COSTUME_KATANA_READY
Mace/Sword/Axe: COSTUME_RIGHTHAND_WEAPON_READY
Pistols: COSTUME_DUALPISTOL_ZOOMED
Rifles: COSTUME_RIFLE_READY
Titan/Staff: COSTUME_TITAN_WEAPON_READY
There are also several poses and the like that use custom weapons. Usually listed under "ENC", "ENCOUNTER", and "COSTUME" in the list of movs on the paragonwiki.
There is also some overlap, such as pistols and claws being fairly compatible with their movs.