If the original weapon is 2 handed only 2 handed weapons will work, other weapon names will be grayed out if they r a higher ilvl, different class weapon, two handed or 1 handed.
It'd be weird to have a thyrus with a garuda's whm wep as a glamour...cuz the shield would be invisible/ non existent? Lol
Probably would be too much programming or something i assume.