Is it company policy where you work for the Captains to mentor Co-Pilots and give them as much hands on experience as possible....or are Line Captains seen to be the Hands on guy and the Co-Pilot there to assist the Captain by doing all the grunt work?
I think you are reading waaaay too much into my comment about the PIC taking control for the DA decision in marginal weather, but here goes anyway...
In my company generally one pilot flies out and the other flies back. I may offer the other pilot the other sector as well from time to time if they are relatively new on line so they can get the take-off and landing practice: regrettably, I won't improve, maybe they will.
As to mentoring, no, I don't think there is any policy about that although I fail to see how you can sit there and not learn anything from watching the other guy regardless of the experience you have.
I always saw it to be my responsibility to teach and mentor as well as be the PIC of the Helicopter.
By doing that.....do you not work to break down the psychological barrier between the two pilots so that in times of stress the subordinate is willing to speak up and communicate and for the Captain to "Listen" to the Co-Pilot?
No, you don't. I think you set yourself up as 'teacher' if you do that and force them into the roll of 'student' and probably considerably steepen any cockpit gradient. Probably better to treat them as as much of an equal as you can and ask as many open questions as you can about the decisions you need to make. Unfortunately, I probably trample all over this ideal the moment I say, 'Well, I'd rather get back to base with more/less fuel than that because of the weather/exposure coming off the deck.'
It probably also helps to tell them before you go flying, that if they see anything they don't like or understand to spit it out sooner rather than later.