Single Player Item-Spell Trouble

[Vash]

Hmm...not sure if this applies to your problem...but I've been playing with my single player S/S Barb for the past few weeks. I found the unique Zweihander (glee!) and it's been serving me well. The sword has a chance to cast fireball on attack. I've found that the fireball is never cast when I whirlwind (is this intended?) and it is only cast when I use "normal-attack-type" single target attacks (concentrate, berserk, etc). I haven't tested to see if the fireball actually does any damage, though.