I've played a lot less than the people here, but it seems those weapons you get from Guild Quests (If that's what you're talking) are definitely locked in when it comes to sharpness. Adds to the MMO-esque pull of Guild I guess?
I swear, if this Silver Los/Gold Ian in the same mission is a Key Quest I'm going to flip my lid. Played some as the first thing in the morning and figured I'd knock out Silver. 48:27. That's how long it took. Why? Because when I'm not impatient in this game I'm apparently too safe. The stupid thing would never land, so I was on the ground with my Hammer walking around for minutes on end. Very annoying way to start the day off.
I then took care of Dahren, Akantor, and Teostra. The former two went down easy. Teostra was a bit of a pain, taking four attempts before finally killing him. I switched to a heavy-Dragon hammer on the successful hunt, so I guess that's what I'll stick with against him until I get a nice Water Hammer. All-in-all, things were great.
Were. Because I just finished the day taking care of the Gold Ian quest. It was pulling the same stunts as Silver. It refused to land. So I tried to get some hits in here-and-there, until I finally just got impatient. And the no-tell charges really did me in for doing that, as in the end I had spent forty healing items, three Steam Bombs, two Traps, and I was on half a bar of health when that thing finally dropped its lousy butt to the ground.
So. I'm glad it's out of the way, but that was one of the most annoying fights I've had in MH4U. Or P3rd. Or 3U.
TL;DR: Basically, screw Gold Rathian.