I think Fighters are in a good place, and I like all the subclasses in general. However, I feel like the Eldritch Knight is a bit behind the power curve and offer the following option.
When you reach Fighter level 10 in this subclass, you can choose to gain the Eldritch Strike feature (as presented in the Players Handbook) or to gain the following replacement feature.
Once per turn when you hit a creature with one of your bonded weapons, you can expend a spell slot to deal an extra 1d8 Force damage to the target, plus 1d8 per level of the spell slot. If you expend a 3rd level or higher spell slot, you can also give the target the Prone condition if it is Huge or smaller.