That's the Persian Persuader, and I use that one too! I don't use stickybombs, I equip the Charging Targe, Persian Persuader and the regular grenade launcher. The Persian Persuader turns ammo into health and recharges your charge 100% faster, so it turns you into a powerhouse at the cost of running out of ammo eventually (only the resupply locker can give you new grenades). It's still hard though, I'm not that good at it yet. Also if your aim is just slightly off, the grenade will miss and be useless since unlike the rocket launcher it doesn't explode upon hitting the ground or wall.
I'm not bad with stickybombs though, it's just that I can't seem to use it with this setup.
Most of my game time is still as Engineer. Especially since I got the wrangler.