Your DoHs or DoLs dropped the ball on the third session. Either the DoHs weren't keeping Defense + Evasion up or the DoLs weren't keeping Attack Down up, or both.

Glad to hear Dean is helping out new Hamlet players. I've done runs with him and they've all gone really smoothly.

EDIT: While you're interested in WHM tips, one of my LS mates started doing something interesting at the start of Hamlet. Use Presence of Mind to cast an extra Stoneskin or Protect at the start of battle. It's not a huge deal, but I thought it was cool.