Effect:
I think that unfreezing is too situational an effect for a weapon.
I would suggest making the unfreezing affect more beneficial so that it would promote

(Flamberge|Squid) decks.
Either make defrosting cause a negative effect (combined with targeting the opponent's creatures or using Ice shield) or make defrosting cause a positive effect (depending on the effect this may still promote freezing the opponent's creatures but may promote freezing your own)
Name|Element relationship:
The Flamberge is a great choice for a Fire weapon. Large and focused on an aggressive combat style.