Assuming this would work like hair currently does, it doesn't actually affect movement/collisions.
This might be good For wearing Bracelets, Necklaces Etc. But other than that i don't see
use for someone holding a Sword, there are mods for that There is no need to try
and create a sword that 1: you cannot use and 2: will More than likely lag the game
for no reason, you can do this with a stable Flame as well.