At this point in time, I haven't seen anything in particular that is "dirge" specific. You should be getting as much positive faction as possible naturally but you should definately get max faction with Danak in Jarsath wastes seeing as the faction merchant there has the ROK "relic" armor. If you get max faction with all 3 JW groups you get a nice hammer that transports you directly there.
Also its in your favor to get some faction with the reet frogloks in kunzar jungle since you will be a problem for your group in some areas of sebilis.
This expansion is all about the factions and the questing. Some of the faction merchants offer some nice items so are worth bothering with

Also, keep in mind that the raid progression might need it in the future and it won't be a class specific thing most likely.