I would consider whirlwind an AoE attack. If my main character survives to tier 3, he will be performing a whirlwind with 10′ radius from a 10′ center, 28 squares in range. So there is a consideration for alternative for the melee attack.
Just in case it ever matters, if you play at my table, you’ll need to roll each hit and damage separately with Whirlwind. Bring lots of dice 
John