But that's jsut the thing. You get three attacks per action. If you're using your action on a hold person, that's a wasted action, unless you really can't reach the enemy.
But that's where, indeed, multiclassing comes in. Want more magic, into to Wizard. Especially Abjurers mix *ludicrously* well with Eldritch Knight, though that is again going the Tank route.
A 6/6 Abjurer/EK can haste himself, cast counterspell and shield and everytime that shield procs - you get stacks of Arcane Ward, mitigating damage, which you can even use to protect your allies. Also get 3 feats for your ASI's or fine tuning. And you can still fling fireballs if you really want to.
