I'm still progressing on him but glyph wise i'm running with Thunderclap for some extra damage but I have been considering unending rage so you can easily put up two massive shield barriers in succession (but we've not really gotten to a part of the figth where what tanks do matter.... my raidmembers and not standing and fire and things... always been a bit of a bitch).
Honestly doesn't really seem like there is some massive trick/tip for this fight for prot warriors. Some go with Stormbolt and precast it while the shredder is in the air but I haven't done that personally and just stick with BB & DR since that seems to work just fine.
You want howl for slowing adds (imo) but that's about it for "must" glyphs/specs.
(Im not even talking about heavy rep & revenge glyphs since those are always a must)