I don't think I've seen this posted anywhere, but biomancy really improved the close combat potential of the humble marine librarian, in particular Tigurius. With Iron arm and a force stave, your librarian can be rolling at str 9 ap 2 at initiative with a toughness of 7 (And concussive). Throw in a possible warp speed and/or endurance and you have an absolute combat monster on your hands.
I am getting Tigurius now so I can try this out. I've always wanted my librarians to be more of a threat in CC