Your lowest levels of beating Ult. Caves

[Gjl]

I did it at lvl 60 with my Soul Eater wielding melee FOmar.

If your having trouble with Ult Caves, then by all means go back and hunt that Delsaber Buster for exp (although of the two items in the Delsaber set, only the shield is worth using later on). If you're OK for Vulmer slaying then I wouldn't screw about hunting the Delsaber Buster when you could pick up a Chain Sawd instead. 1/1050 is not difficult at all, especially on a very common enemy like a Vulmer. Addicting Foods has 184 Vulmers...Plus Skyly has some reasonable drops overall for Caves, so you might pick up a lovely pair of Red Daggers or even a Demolition Comet if you bump into a red slime.

Just make sure you don't actually complete the quest (ie. don't go back to the Hunter's Guild, just save & exit). If you do complete the quest accidentally then you're gonna have to do EVERY other quest in the game just to be able to redo the quest.