Sasstar told me about this yesterday when we were busy heroically wiping on Kael. If you have Shadow Priests in your Guild, what you can do is have them cast rank 1 Shadow Word Pain repeatedly on all the weapons during Phase 2. This will stack the Shadow Weaving debuff (which increases shadow damage by a lot). Just cast Shadow Word Pain back and forth on the weapons.
Your Warlocks will love you.
By utilizing this, we’ve managed to kill the weapons quicker and get into positions for Phase 3 when all of his advisors are back up. Our best has been Phase 4. Sunday we’re going to spend the entire evening from 1630 – 2100 on Kael. Hopefully we can take him down early, go back to SSC and clear out Vashj.