Wizard of abjuration school only have a weak and useless arcane ward with 3 hp at level 4 with 18 int, it should be wizard level * 2 + int modifier which is 12 hp. Also arcane ward does not work like a temp hp and should not be overrided by effects that gives temp hps. Besides, arcane ward should be rechargable, so the buff should not disappear if it breaks, instead, casting any abjuration spell with more than lv.1 should recharge 2 * spell level hp to it. Also lack of reaction spells like shield and ritual casting with alarm makes abjuration wizard weak.