I think many modders wanted to place new weapons on their servers and i know the usable names for viewmodelanims are programmed in the engine. It would be nice a script command like "viewmodeltype" or something. For example the modder write this in the weapon.tik "viewmodeltype ppsh" and the game will know that it have to use for _idle, fire, reload etc viewmodelanims to the PPSH weapon.
I dont know if it's possible server or client side.