I'd probably go Grenadier with the idea that the sooner I drop 'em, the sooner I stop being delt damage. Hasn't the best defense always been the offense?

http://zeus.jrq.ch/trcb/?x=30240811111000005000005561005068068068

My skills rely on dishing the most damage possible, firing a first shot of Rocket Launcher then switching to a Propellant Gun when the Bane closes in.

Rage is a strong skill here because it's geared towards what I exactly want to achieve: Lots of damage.

Sacrifice is a promising skill too, but at level 5, it burns 10% of my max health per 5 seconds. That means that in less than 1 minute, I die if I don't turn off this skill. The 150% dmg bonus is nice, but perhaps too nice as it will quickly consume me in the process.

So all I want is 1 rank in Sacrifice meaning I get burned for 2% of max health which is more easily sustainable and I still get a 70% damage bonus. A 1000 dmg shot will still get upgraded to 1700 dmg which isn't bad at all.

Now I don't know if Rage and Sacrifice will stack so I'll make sure to have my answer before going with Sacrifice.

Finally, I plan on doing some PvP later on and I feel this built has a chance of helping out in those occasions...

From what I have read Sacrifice and Rage stack.  Rage 5 plus Sacrifice 3 or so for big targets equals instant death for the enemy.  While doing the haloween missions on the other planets I checked the stores.  The damage your weapons will do goes up to some silly numbers.  Stacking those two abilities can make for some amazing things.