I think going DW is perfectly viable for raid tanking - just depends on what you are going for. Leaning on a lot of what has already been said: Increased Aggro / DPS: DW with Finish the Fight or Dragon Glyph running covers what shield would have done for you (minus the +870 AC or so). Increased Survival: If you want to save Finish the Fight until Defensive is down, you can use Shield for the 2k hit absorb, then raise it with the FTF 6230 later. Just a question of what is more important to you.