The Magic Weapons of Ice And Fire (ASOIAF/ Game of Thrones Theory)

In A Song of Ice and Fire as well as the show Game of Thrones we see the others have a magical weakness that results in a one hit KO. These beings of ice magic melt on contact with dragon glass in the books and Valyrian steel also has a similar effect in the show (and probably will in the books as well). This brings up an interesting question, if the magic ice monsters have a weakness to fire magic weapons, do the magic fire monsters also have a weakness to ice magic weapons? Well there is one character in the history books named Brandon Snow who seems to think so. The half brother of Torrhen Stark the king who knelt had a secret plan to wipe out all three of Aegon the Conquerors dragons in a single night, and it turns out that plan might have worked. Will this set up have a pay off in the future books? Do Dany's dragons have a secret magic weakness we have yet to see confirmed?