This is really a quite popular support build.
• Skill build is fine.
• You could wear full plate set in armors (you don’t have to worry about this until 170 or 220 as quests rewards will provide you the sets through certain points).
• As of weapons, you could basically get any weapon especially those that adds HP or AoE ratio. Or you can get yourself an Audra for +2 Cryo skills. But it’s not really necessary as you are a support and wearing a shield is a must.
• Leveling your skill attributes especially on Ice Spike will help you a lot during lower levels.
Note that no matter how you level your Ice Spike and get as much magic damage you can, your damage will really fall off past Lvl 140. This class is extremely hard thus I recommend finding a party in doing your quests.