Somewhat of a moral predicament

[Duo]

Well i'm in a bit of a tight spot. Recently online i was given a Tsumikiri J Sword + 50. Note GIVEN and i have a really bad feeling (basically i almost know) its a dupe. But they guy who gave it to me said he traded for it. Now here's where it comes in, i really REALLY want to go to ultimate so i can get my own rares but i'd die instantly if i went in ultimate alone any time soon. Here's the thing, do i use the item which is more than most likely dubbed to get my own rares, drop it and never use it again or just give it up now. I really find this tough because the urge is so overwhelming that i wanted to ask for advice, which way to go, the easier and quicker way or the harder way. It sounds easy but its really not for me. Please just someone say something so i can get over it. Sorry if i'm making something small seem big.