No, it's exactly the same power. The problem is that Amiti is a mage, and has no business using Piers' warrior class like that. The reason it's weaker is because he's stuck with mage stat growths and mage equips - of course it does less damage. It's power, though, has always been "Attack +92".
Alex I don't think would use this move at all. From everything we've seen, he's a water user, not an ice user. He'd use something else, likely unique to him.