Other than the low-hanging fruit this entire tree is weaksauce.
Tried out being mostly tempest for two weeks an a toon that was mostly AA then switched back to her normal "melee mutt" build. Dumping the Tempest stuff down just enough APs to get 90% off-hand and hast boost . . . the DPS loss for gaining back the slayer arrows is so little (EE Sobrien melee beat-down times went up be 2 seconds) that I cannot say a high investment in Tempest at all is worth it.
The upper teir stuff . . . all ****. I've never noticed having improved evasion or not . . . 1000 cuts sucks, etc . . . all the top end stuff is so bad.
I'm not sure what to do to fix it either.