Are DM has acquired one of the limited edition copies of the game and so we made are characters, a trader, a militant, an explorer and me the navigator. The class I was playing had a very powerful effect that had limited uses based on my toughness so i had used it once in the session against a few orks then came the pysker (dear empire a psyker) with a few guards she made a roll against me with a telepath power, being the navigator my heavily invested in will was very high and even on the fluke roll of 10 I still apparently lost by 3 degrees. The psyker was taken out by an insanely lucky roll before I was knocked out by her power but its the fact the NPC pyskers can use these powers multiple times and have a low percentage risk of gaining perils that only pc's ever worry about because NPC's don't care about corruption they don't exist off camera its the massive boost pyskers can give to there powers dark heresy psykers where incredibly powerful I thought that since they paid for all there powers it would make them less so in rogue trader but its the ability to boost the opposing check to unmakeable amounts that makes this a class the player fear even if there's only one. I would rather tangle with a tyrannid at least I had a chance to avoid there attacks so has any one had similar thoughts on rogue traders change to pyskers.

One solution would be to play a pysker but I enjoy being a Navigator but it makes it less fun that this class exists thats yours and more.

sounds to me more like a problem with the GM than the actual rules. Sure it can be looked at that the NPCs don't have to worry about perils/corruption etc since they exist for this one session but thats just the mark of a lazy GM. Even if a character is only going to be in a single session the GM should still be portraying them as a normal character that has aims, cares about their future wellbeing etc. The don't need full stories about their objectives but they should be a bit more fleshed out than their sole aim being to fight the party to the death.

You have to remember that a navigator is not fully a psyker - he's a mutant with a few abilities that overlap into warp sensing/manipulation, but he's not considered fully a psyker. If you want to play a full-bore psyker, there is another career for that.

Also, sentences like the following do nothing to clarify what you're looking for:

The psyker was taken out by an insanely lucky roll before I was knocked out by her power but its the fact the NPC pyskers can use these powers multiple times and have a low percentage risk of gaining perils that only pc's ever worry about because NPC's don't care about corruption they don't exist off camera its the massive boost pyskers can give to there powers dark heresy psykers where incredibly powerful I thought that since they paid for all there powers it would make them less so in rogue trader but its the ability to boost the opposing check to unmakeable amounts that makes this a class the player fear even if there's only one.

I was thinking of mentioning something like that to him that few psykers would push themselves but its adding there psy times 5 to there opposing will checks that makes them such a nasty fight.My example was just an example of how incredibly difficult they are to oppose.

If that was the Psyker in the adventure in the main RT book keep in mind that she is pretty **** powerful as I remember. She's at least 4 psi. The astropath class in the RT book starts out with a psi of 2! By the time an astropath gets a psi of 4 you'll be able to crank a power or 2 to will +20. Personally it just sounds like your GM just rolled really well.

As far as NPCs being able to crank up the power without worry about corruption/insanity. PC psykers do the same thing if they are at risk of losing or dying. It's just that as PCs you are nearly always a threat requiring full power. If I was a psyker player head to head with a navigator I'd pull out all the stops too.

Keep in mind that as a navigator you have a very limited set of powers. I'd get a decent weapon to deal with things like psykers. An over charged plasma shot or flamer is going to ruin their day unless they've got a TK shield up. Using a power with a will save against a psyker isn't a good idea.