If you look under Assignments in your crew/ship menu you will see each station to which each officer is assigned.
The rank of each station depends on the Tier of your ship and the type of ship. For me as a LtC Engineer in my cruiser I have 1 Ensign Tac station, 1 Ensign Engy station, 1 Ensign Science station, and 1 Lt Engy station. This means I can use a Lt level Engy skill from one of my engineers but only Ensign level skills from everyone else.
If you were in an escort I assume you'd have a Lt Tac station instead of an Engy one and therefore be able to use a Lt level tac skill.
This is why many Tac Captains often feel slightly gimped if they choose to fly a cruiser instead of an escort because their tac officers will NEVER be able to use their high level skills because the ship stations do not allow them to do so. I liken it to trying to win an Indy race with a semi, sure...you can take the hits but it's not built for a race.
On the ground BOs are not limited by "stations" and can use whatever skills they have trained.
You can put already assigned Boffs in the exchange?
I don't think you can... can you? Because I certainly haven't seen any on the exchange that are trained up.
I don't think it's a good idea either because then you have people selling pre-trained BO's but you can't tell how many ranks they have until you buy it.
What would be better (and probably easier to program) would be if a teammate joins you on your bridge, then they can right-click on the BO and train them in there. Or if when your ships pull up alongside each other, then along with the "trade" option showing up, a "train" option would show up.
I think it's lame too, because due to not knowing the Connie was going to be a piece of crap Light Cruiser, I bought an Escort, and then I have been putting points into Torps because I wanted to be able to train up my BO in HYT III. Of course, now you're telling me I can't, because I'm an Engineer.
Logically it makes no sense why an Engineer could not train someone in a skill they knew, whether it was a Tactical skill or not. Sure, if they don't KNOW the skill, but seriously, what is the reasoning behind this? If an Engineer can fly an Escort and use the skills, what would there be to prevent a BO from learning on the job from them? I think the real solution to this is for Cryptic to simply fix this problem by letting characters train people in any skill they know.
Being an Engineer in an escort is already crippled enough without the game lying to us and telling us we can train people in skills that we have, then we find out we can't.
Well this sucks. Im Engineer in a Escort and want my High Yield 3. I spend skill points on it, and it didnt say Tactical Officers only.
I guess all i can do is wait for a mission that gives me a rare Bridge Officer with the ability and look into the exchange every day. ...
I think the real solution to this is for Cryptic to simply fix this problem by letting characters train people in any skill they know.