Hey guys, thanks for the comments. Hate to disappoint a couple of you but in the end I went with the maul on Sergeant Corvinax and the chainsword for Sergeant Icarus (Yup, picked a name for him).
I'd issue a warning about the poses. The maul looks more natural. The gun also to me looks overlarge to be used in one hand (even in the arms of a supersoldier)
My philosophy is that a model should look balanced and realistic. You've got 'awesome' pegged, but from my end, you've missed some fundamentals.
I can see where you're coming from, it's not something I considered too much. I think with the Combi-Bolter it's not too much bigger than a standard bolter and there's plenty of precedent for marines being able to wield bolters one handed. There's also wysiwyg to consider, if I want to play him with a combi-bolter and power maul he's gotta be carrying a combi-bolter and power maul.
Maybe with the storm bolter I could agree. I wanted to have the sword though to help mark him out as a squad leader though. Could have sheathed it, yes but I don't want to end up with the squad all in similar firing poses.
Thinking forward on what I plan on doing these should be the only two guys that this should be an issue for but I'll definitely consider it more in future.
So, update time. Progress has been slow on my tactical marines. The next five members are not far from completion though. That does bring me to my next point though that I could use some advice for.
This is the Sternguard Heavy Bolter with the arms it said to use, on a normal tactical marine body. As you can see, the arms are wider than the body. I'm guessing the answer is going to have to be green stuff but I'm wondering, as my green stuff skills are non-existent, if anyone has a simpler solution.