You've just got to put shield swipe to better use. Most people seem to think its worthless and yet its essentially a PLDs version of invigorate or the WARs new TP restore ability. Its now a DPS loss but sitting around with 0 TP is a MUCH bigger DPS loss. Floor 4 Alex is an exception because you basically have 100% uptime and cannot block attacks (so far that I've seen). In that case you really just need Paeon or Goad. I've run low on TP but haven't bottomed out yet.

On the other hand if DPS is so bad that fights are taking an extremely long time, well...I suppose there isn't anything you can do about that except run with better DPS :/