For a while now the perfected master weapons have had this visual bug where it doesn't actually show their unique visual glow effect when you unsheathe or bar swap to them. Instead whatever glyph enchantment that is on the weapon seems to override it. This isn't the case for the normal master weapons however, which are still visually working as intended.
Its a small issue but it seems like it would be an easy fix since the bug has happened before and was fixed within weeks before later bugging out again.