But situation is gooooood in this case and doesn't hurt your card at all. Freezing is something water does very, very well, and many deck concepts make use of it.
Freeze is powerful but it's also temporary. Have you used Permafrost much before? Stupid question probably, but whenever I use it, I find the freeze effect to be very reliable. Random, yes, but it doesn't usually take long for everything to freeze repeatedly. You'd just wait it out and pop this card to seal your opponent's fate. Freeze-shockwave requires a duo deck, I wouldn't call this redundant at all. Especially since it's 1) not instant kill and 2) hits every [frozen] creature.
Anyway, most 1-2 health creatures don't have very high attack, and wouldn't be much of a concern with a shield out.