We saw two of these in 12 weeks, with the last two weeks having reduced lockouts where we could double up, not sure "common" is exactly accurate.
As far as the sword itself, it procs a lot, enough so that the HoT almost never wears off in combat ( assuming it isn't overwritten ).
It is in fact, a 1hs, not 2hs.
Great weap, best of luck Pallys...and I suppose SKs...