Glamour (Item) Level Flaw

This isn't new but I'm just wondering why it has to exist the way that it is when my "Job Level" should be how it is assigned instead of "Weapon Level"?

The problem:
I wanted to glamour "Riversbreath Faussar" which is a Lv.91 DRK weapon. I am currently a Lv.91 DRK. This weapon is item level 650 and does 129 Physical Damage. My current weapon is Lv.90 but item level 665 and does 132 Physical Damage. It is BETTER than the Lv.91 weapon, because of item level of course.

So instead of being able to glamour the Riversbreath Faussar I have to USE IT, but if I use it I am purposefully nerfing myself just for a glamour.

How exactly does this make sense?

The only explanation is that they don't want people to have a Level 1 Weapon and able to glamour a Level XX Weapon instead, BUT the game should not have to check that flag in the system when it could just look at your Job Level instead to see if you CAN use it.

IF "Job Level" >= "Weapon Level"
THEN "Glamour" = YES
ELSE "Glamour" = NO