Penko,
If either crewmember has a concern about the conditions, it will be discussed. If one person isn't comfortable, the other will fly. Pretty simple. That said, the prevailing attitude here is that there's only one way to get comfortable landing in a 38kt xwind. (Hint, giving away those landings isn't it)
I'm a new A320 FO (200hr on type), and I'm yet to see 38kt. The last time I had a reasonable xwind, the CA and I discussed techniques for xwind landings as part of the approach brief.
At a prior company I flew with CA's who'd never seen a strong crosswind before, as they were new to the type. What would you do in that situation?
Well one difference is that the Captain is responsible for the operation.
If it goes pear shaped it is his/her career on the line if no other consideration.
I can assure you that even though the CA is responsible, if it goes pear shaped, the FO is going to be doing a carpet dance as well!
Some FO's I'd trust with any crosswind, purely because I have watched them land before in challenging conditions and know their abilities.
Perhaps we come from airlines of different sizes. Your theory is sound, but at most airlines here, it simply is not practical to do that, as it's quite likely that you've never flown with your FO before, or your last flight with him/her was a long time prior, and you have no recollection of the trip.