Yes, it can be polished. Ernest Langdon used to do outstanding -- and very inexpensive -- work on Beretta triggers. If he were still in business, he'd be the only way to go.
But he's not, so I'd try the following easy solutions before moving metal:
- Detail strip the gun and gently polish any action parts at any point where they show obvious wear from contact with other parts of the action.
- Apply a good grease, like TW-25B, to all the friction points of the action.
- Consider finding and using the "F" model hammer spring from a Cougar. It is lighter than the 92D spring. However, it may not last indefinitely. To be on the safe side, I'd probably replace it every 10k rounds if it's remaining reliable. If I could get a bag of them for cheap, I'd replace it every 5k rounds just to be on the safe side.