yeah the answer might lie in a warlock specific "tenser's transformation" like effect, where the warlock can gain a lot of this martial juice at the cost of a spell. Its not perfect, some would still scream that the warlock can do everything a fighter can do + spells, but at least they would have to give up spell power to gain martial strength.
Although honestly if they went back to 2 attacks it might be fine. I mean the bladelock gets lots of cool stuff, every weapon mastery, different damage types, auto use of charisma on attack and damage, never disarmed, its a pretty solid list already.