Nobody played it in 2011. The game launched in October 2012. The weapon you're holding was released during the winter after the cap was raised from lvl16 to lvl21 (dead city). It came along with the green and blue winter armor of which now a vanity set are available blue and red. Therefor no lvl30 exist of this item nor a l26.

When you reached lvl16 cap, granting you the l16 banner, there were elite maps too. Granting you the elite title. You may have farmed maps and elite maps gaining many kills at that time. The stats and weapon seem all straight forward to me. (yes, i too played at back then and i also quit back then)

I never heard of a bug setting you back 10lvl's nor even 1lvl. If there was one, more people would suffer from it i guess. It's more likely you forgot which lvl you were, no offence.