So I got the sword from LFR Amber shaper last night and I'm looking to go DW when I get a normal 1H, I've been looking into it and the rune of choice is supposedly Razorice, which obviously for a single target fight makes sense, and for AoE it is Cinderglacier, my question is: where is the line? For example on Wind Lord would it be best to use Cinderglacier for the whole fight or Razorice? This is assuming that there is no weapons to swap, and on that note would it be an idea to have a worse weapon with Cinderglacier to swap with for AoE? For example if you had one ilvl 489 and two ilvl 476's and to swap the 489 with razor to a 476 with cinderglacier for aoe phases?

Sorry if that seems a bit messy.