Does the level at which a Psychic power is used (fettered/unfettered/push) modify the Focus Power roll in any way? If not, what are the benefits to unfettered or push level attacks with a Force Weapon?

I don't think they do in Deathwatch. I know they do in Rogue Trader though (there's a flat +5 per effective PR bonus to the Focus Power test in RT…this would include the test to channel through a Force Weapon).

It seems this mechanic was removed in Deathwatch.

No, the same mechanic is in place. +5 per PR.

Usual is right, for every PR you use on a power (including the +3 for pushing) you receive a +5 to the focus power test.

So a WP 50 librarian with a PR of 5 will be testing focus power on 60 for fettered, 75 for unfettered, and 90 for push.

Unusualsuspect said:

I was looking for that but couldn't find it. What page is that on?

208, focus power tests, second paragraph.

Thanks for the info.