That's the encore upgrade.

Exactly, meaning as long as its Melee enemies you can chain it for quite some time (unless Ranged or AoE's hits you). Possibly troublesome in PvP but don't see a problem in PvE. Trash is just trash, but Bosses won't (shouldn't I think) die in one hit. I won't care in the end, since I do not do PvP and have no interest in Hunter. I'll let the Devs look it over once Launch comes and they have some meta-data to use from PvP/PvE.