D&D 5E Thoughts on Mearls' Comments on Fighter Subclasses Lacking Identity

[Flamestrike]

It would tie fighters to a single weapon. That is somethinng the designers didn't want to do from day 1. It was a perceived problem on all editions since UA introduced Specialization.

Ive done this with a feat.

Weapon specialisation
Requirement: Fighter 8
Select one weapon. You get +1 to hit with this weapon, and deal extra damage with it equal to your Fighter level/4. You can change the weapon you selected with this feat to different one. It takes 30 days of downtime activity to do so. During this time, you lose the benefit of this feat.