I think the free answers are going to be trait upgrades (eg Melee Mastery), a new oGCD that isn't gauge locked and instead runs on a timer (like Gluttony, only I expect this one to give gauge rather than consume it) and a GCD follow-up to Communio (ala Paladin swords after Request Cat).

The base is already pretty streamlined as is, but there are a lot of spaces they could add in a new oGCD. Having it generate gauge would also help prep you for the Circle window since your GCDs in there are going to have to be Communio-follow up and Bountiful Harvest. I say 'have to' because I doubt they'll let you just build up stacks of the follow up, it'll likely be use it or lose it. This kills the Triple Communio meme but I don't think SE was ever fond of that in the first place.

As for what I'd like to see? The Communio follow up, it can be either GCD or oGCD. I like the hit visually and want to see it expanded on. From there it depends on whether they want RPR to be on the utility scale. I'd be fine with being the lowest damage melee if it meant having some interesting utility. For example, it would be cool to have a larger shield like Crest that you plop down around you, and it absorbs damage dealt to anyone inside up to a cap. That's a pipe dream, though. It would be brokenly overpowered for the way this game is designed concerning mit if it was actually useful. And if they want it to be higher on the dps scale, well we don't really need new abilities for that. That's just number changing.