[@Necroes] reading your characters description i get the feeling you are on the level of a big nob.
Seeing this is an RP, i assume the marines are fluff correct marines and not sissy tabletop game marines.

Meaning a single marine is roughly on par with an ork nob. One must play his cards right, or the other will use their strengths to defeat him.
Being a psyker is a great boon here though.

However, there are two marines. Sure, having a force weapon is a good tool, but there is no certainty in Urgrugg defeating the marines.
In an one-on-one, sure, he's got very good odds of winning, but two?

I base a lot of the marines power on the game Deathwatch by fantasy flight.
The marines in that are DEADLY!
With some luck, kill a meganob in CQB with a chainsword. Paste orks for sports.
Only ork capable of making a group of marines think twice is a proper warboss.

So looking at all this, why would Urgrugg so easily win over the crusade era marines so easily?
And if he didn't want to kill them, has he no control in how he fights? He could just knock them out, seeing that he's so good at close combat.

I myself is lucky i had begun to dissipate, otherwise i would be dead.
Had the bolt round hit i think i would play it super badass main character mode and survive. But it would mostly be the stereotypical final last word. Perhaps doing something cool.
In a straight up fight, nooo, a marine could pulp my character with his bare hands. And these guys got bolters, CQB weapons and a servo harness.

I'm just wondering why Vedius started firing on me.
I guess i look creepy, but is that enough to warrant killing me?
Dunno. Perhaps he's used to chaos and know the callsigns.