Well collector weapons come with perfect mods and are blue, but as far as I know there are no collector's or weaponsmith's which give out r10+ weapons. So yeah this is weird.
It's not a drop. If it's real, it's probably some obscure collector item or quest reward item.
I highly doubt it's some 1 of kind only blue max q12 15^50 item ever dropped in guild wars. Much more likely it's some obscure quest reward or collector drop.
Maybe someone can rule this in or out, is it by chance the long sword given during the Custome Brawl as part of the disguise (I don't know off hand which req is given), but wiki does have this for Long Swords "Provided as a default weapon for warrior characters in the Costume Brawl (customized, blue with +15% damage while Health is above 50%)."
I still have the scythe I got from Costume Brawl. I can check that, when GW is back up. I also considered it just being Jora's sword, but that is r9 10/st.
Maybe someone can rule this in or out, is it by chance the long sword given during the Custome Brawl as part of the disguise (I don't know off hand which req is given), but wiki does have this for Long Swords "Provided as a default weapon for warrior characters in the Costume Brawl (customized, blue with +15% damage while Health is above 50%)."
you're probably right 
