A Relic Reborn question

[Theref]

I'm on the part of the quest where i have the precursor weapon, and the materia, but don't have them melded yet. I was told that i shouldn't equip or use the item until it's melded, but others have told me it's fine. I pretty much spent all my gil getting these things off the Market Board, and all the crafters want 20k gil to meld them, but it may be a while before i build up to that again. The weapon is a good deal better than what i have even without the materia, so it would help me to use it, but i really don't want to bone myself on the quest for the relic.

Anyone able to give me a definitive answer as to if i can use it before melding?

You can use it or not. Of course if you use it, the weapon become bind to you so you can't trade it.
But to Meld your weapon, there's "Request Meld" menu when you right click on the person, that way you can meld things that bound to you without having to use Trade.