By reducing duration and increasing damage you are not really solving any problems. Blizzard spell is hard to use since it damages your own units, for teams vs teams its not bad when there are a lot of units. But in 1vs1 its only good in late game.
This is how I would solve Archmage and Jaina since nobody ever gets both Blizzard and Water elemental, instead its always aura+blizzard or aura+water elemental. People want more spells early and these suggestions also solves that. In WoW classic Blizzard spell doesn’t deal friendly fire and it’s fun when the duration is long, because you are supposed to move out from it. Blizzard spell has always been long duration even for Warcraft 2, you should not reduce the duration since you are removing the epicness of the spell then.