Is it possible to do a pure Fig20 Kensai III arcane archer if you've got a sorc past life? I wanted to do that originally a year and half or so ago, but it wasn't possible then, so I went with the 1 ran/1 bar version similar to what's posted above.
It looks like they added the sorc past life feat to the list of prerequisites so maybe it's possible now?
With a Sorc past life yes it's completely possible but safe to say pointless. You will have minimal SP so 1 maybe 2 imbues per rest, the fighter capstone is useless to an AA and without the splash you are lacking in a choice of many things eg. Evasion, trap skills, songs, self buffs, automatic feats etc.
Yes, a 20 fighter AA is possible but imo pointless.