I have gotten plenty of clothes with spells that cost 8 or more pips that are not in my school range, How would i use those spells if i dont have an mastery amulet and if i need one, then why put those spells with the clothes in the first place...... I am beginning to think that they put those in there to get more money from players.
Those are for players that are from the school of the spell. That's why most of those clothes have the emblem of the school on them. To show that they are rare and are supposed to be for a certain school.
Some of them have lowered pip cost but you can't force the ones that don't to not have the appropriate pip cost. They are for the other schools. You can't force the boss you won against to not give you a certain object just like that. Just like how you can't force Malistaire to only give you your school clothes.