EzekielRaiden
Follower of the Way
Make it require level 11 and consume the use of your Bonus Action in order to make use of it. Slightly better than two weapon fighting, but not massively so, seems no more valuable than some of the strong feats out there. And suddenly most spellcasters are a lot less interested and many other characters are disinclined to pursue it. Could be nice for Champion Fighters though, who may not have anything to use for their Bonus Action, and who get more benefit from making lots of attacks.
Edit: Heck, just add to the above that it requires you have already gotten the Extra Attack feature from some other source. That means you'd need 5-6 levels in one of various classes just to qualify. It's certainly strong, but that level of investment guarantees most people won't take it, and it would be competing with options like Polearm Master. This would also shut down concerns about stuff like Rogues getting ridiculous sneak attack opportunities (since Bonus Actions are actually precious to Rogues and investing 5-6 levels in some other class is rough).
Edit: Heck, just add to the above that it requires you have already gotten the Extra Attack feature from some other source. That means you'd need 5-6 levels in one of various classes just to qualify. It's certainly strong, but that level of investment guarantees most people won't take it, and it would be competing with options like Polearm Master. This would also shut down concerns about stuff like Rogues getting ridiculous sneak attack opportunities (since Bonus Actions are actually precious to Rogues and investing 5-6 levels in some other class is rough).