New (better) quest armor not equipped

[Zenobia]

So how do you know what weapon can be equipped by what class?

It' quite frustrating. My current weapon is 76 attack and 94 defence but I've just won one that has 102 attack and 92 defence. It's very annoying that my guy won't equip it.

Nowadays it is usually indicated in the group LTE spreadsheet. In general, logic actually does apply though. If it is large and heavy looking, it's warrior class. If it's daggers or a bow, it's rogue (though it is very typical for a bow to actually be all-class). If it's an orb or tome or staff, it's for a mage.