My question is, is this simply a random generated sword or one of the GM stuffed weapon? I'm more wondering if its possible to get 5x or even 6x weapons randomly in a the treasure system?

To me it looks like a random treasure gen, Typically if a GM makes something they give it more of a description.

And to answer your second part, yes +25 gear is often found from random treasure gens and hand made GM items. I have never found anything +30 or above, but I know a few who have found +30 gear.

From what GM's have said it's possible to find a +50 claidhmore the way it is set up, I just wouldn't honestly expect to see an item over +30 in reality (those are pretty rare as it is). There may be a "chance" for something nicer but it's so low I doubt anyone ever finds something nicer that was not hand made by a GM.

I up hunt (5-20 levels typically when I do hunt) and group hunt (from one friend to 5) a good bit and I've found some really nice stuff, but still nothing over +25 enchant in any of my boxes.

Senglent and his wayward kin.