My build, Barrage is bad to try using especially off cd, every Ripper will realize this after playing it enough and checking skill description in damage meter.
You're missing the point that it has a 5 sec CD while under the effects of Arsonist, and that it triggers your Class Mastery II, which essentially doubles it's damage from 1527% to 3000%+. It's also part of the 3 skills which you spam under your ulti.
You're seriously underestimating Shift Blow. It's a very decent skill imo.