It's almost impossible to have a favorite weapon or find skill with a particular loadout. As soon as you level, you either have to spend cores you don't have, or you have to move on to some random roll trash weapon. And the random exotic drops mean that if you don't infuse your favorite exotics, you may never get a better levelled version ever again. I pulled a weapon from my collection and it was more than 20 points lower than my max level. It's incredibly frustrating.