You could even attack with bare fists if you were carrying a weapon in both hands (though I don't know why you'd want to).
I actually did that once, before they changed Blast to be optional. A Crushing Block trap during a battle action left Spiritspeaker Mok with no LOS to his original target, no fatigue left, adjacent to a bane spider and another hero, and equipped with the Ice Storm (which has an inherent Blast 1). Any attack with Ice Storm would have hit himself, plus the other hero, and (unless I rolled 4+ surges) only one monster. Also, as it happened, Mok had drawn the Mighty skill at the start of the quest (+2 damage on melee attacks).
Opened up LOS and let him kill 3 beastmen with his second attack, too.
Not exactly a typical situation, though.