black robes

[Akhulas]

then you roll an draconian transmuter you cant choose alignment - all draconians evil. but you see something like that:
"You must be of evil alignment.
Your alignment is evil, you will be a black-robed mage."

but there is a courple of items black_robed_only. but you cant wear it. why?

<731/731 226/853 289/291 720178 NSW> cast ident belt
You recite your magical incantation.
Object 'belt dried flesh' is type armor, extra flags glow.
Weight is 4, value is 8800, level is 19.
restrict flags black-robed_only.
Armor class is 8 pierce, 8 bash, 8 slash, and 8 vs. magic
Affects intelligence by -1.
Affects armor class by -8.
Affects mana by 35.
Affects will save by 3.
Affects reflex save by 3.

<731/731 202/853 291/291 720178 NSW> You stop using a velvet sash.
You wear a belt fashioned from dried flesh about your waist.
You are zapped by a belt fashioned from dried flesh and drop it.

[Kiri-Jolith]

Black robes are necromancers.