You can refer to the screenshot in the following thread as reference. That my dual wield warrior stats during end game
http://www.larian.com/forums/ubbthreads.php?ubb=showflat&Number=396848#Post396848 As for non set gear, I prefer the heavy/ elite champion set for my warrior, since I like the champion set skin over others.
For set gears, in my own opinion, those archmage, scorpion and hunter sets are kinda junks. Those are the 3 sets which consist of 10 parts to consider a full set. I myself prefer ultring set, which only consist of 4 armor parts, providing more enchantment and charm slots, as well as better set bonus to me. And most important, the flexibility of using legendary accessories than limited by those in the 3 above set which give you crappy necklace, rings and etc.
I dont know if your fire blast is fire breath or not, as I only fire breath and fire sphere. Fire breath is the default attack skill of dragon, just left click the mouse and fire will auto breath out from your dragon. If you are on 360, then I really no idea which is its default button. Maybe just try check on your config. For fire sphere, just put it to the shortcut key bar, aim a target and press the correspond short cut key to fire a fire ball out from your dragon.