Along with what other people have been saying, the 3 seconds of the new status effect will be a bit much.
How about if you hit all 5 shots on the same target, then doomed will be applied for 1.5 seconds? That sounds like a good trade-off.
As for the blackmarket, that sounds like a good idea, where certain dungeons could drop schematics or parts for other items to be created? Maybe a forge instead of a black market per se, that way, fame would not need to be used. However, possibly to revert it back into the original UT, you would use fame.
Just thoughts. Love the quiver though.