If he was already fun enough to play to 40 without choosing his last two powers, that's a good sign.
So.. You aren't tanking, you aren't dps. You can do both but neither is your main thing.
If you are already basically happy with your build then I would recommend looking at Unstoppable + Unbreakable. Unbreakable is a good 'Oh Nos!' button for when things get overwhelming and Unstoppable will nearly double your dps for those times when there is a solid tank in the team or when you just wanna make things go poof faster (Q hour, etc). It has Knock resist built in, too. I always like that.
My Unleashed (after much practice/tweaking) can tank all Alerts in Melee role with Unstoppable, except Gravi, so, it's not like you'll become paper but it is of course significantly less protection than Invul, which, you won't care about if you're teamed with an attention hoe tank. If the tank drops or you're in a situation where you're getting smacked a lot - hit your Invul Build. Unlike Defiance, Invul doesn't have to warm up it is gtg on activation.
Quarry and Earth Form would work as Offense passives, too, but I think energy return in Unstoppable scales off of Rec and it also gives you moar DPS in exchange for being primarily a melee Passive, which, suits your build fine. I think it gives you energy back on Knock, and, you have some Knock.
A classic choice would be Masterful Dodge + BCR w/Resurgent Reiki. BCR adds another layer of healing to help keep you topped off & combined with Masterful Dodge you get a solid 'oh nos' button.
Masterful Dodge + BCR + Devour Essence (I use it w/phlebotomist advantage but I have poison already in that build) is a fairly wondrous thing.
Earth Splitter is a fun Heavy Weapons attack... It's not bad CC either. But then they gimp it by it being Ranged & part Fire damage /rollseyes. It's still a must-try for any Heavy Weapons user.
As j00 know.. since the powers in question are your last 2 they are cheap & easy retcons..