I have no idea about the Free Action from the FoA. If it doesn't cancel however, FoA is probably the best weapon in the game. Combine with AoU...wow. Plus, you can dual FoA and Frostreaver in BG2, which is better than Stonefire (plenty of creatures have fire resistance.)
If you want to go with something else, the ones that immediately spring to mind are Storm Star, Blackrazor and the Answerer. My advice? Have all of them
. Blackrazor is an amazing weapon, the only strike against it is it's +3 nature, which is pretty low for ToB. Storm Star is IMHO woefully undervalued, and in terms of mobs, priceless. The Answerer is great for shutting up mages, and if you grab a HLA of Resist Magic, and some other MR increasing items, you should have no problems with mages (who are probably amongst the toughest foes for a solo warrior.)