Here are the commonly thought best ice-only gear for levels 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50. Some items are in two level categories because there is no item of that level.
And here is a video showing the best gear for max ice wizards
Level 5+
Hat: Fur-Lined Hood
Robe: Sapphire Studded Cloak
Boots:
Wand: Staff of Icy Doom
Ring:
Athame: Insulated Dirk
Amulet: Flash Frozen Choker
Pet: N/A
Deck:
Level 10+
Hat: Warfather's Mantle
Robe: Gladiator's Raiment
Boots: Northland Footwraps
Wand:
Ring:
Athame:
Amulet:
Pet:
Deck: Novice Ice Deck
Level 15+
Hat: Bitter Cap
Robe: Flarefrost Longcoat
Boots: Flarefrost Footwraps
Wand: Runed Sapphire Wand
Ring:
Athame:
Amulet:
Pet:
Deck:
Level 20+
Robe: Krokhotep's Vestment
Boots: Polar Shoes
Wand: Edo's Glittering Staff
Ring:
Athame:
Amulet:
Pet:
Deck:
Level 25+
Hat: Old Smokeys Hat
Robe: Crusher's Winter Vestment
Boots: Frostsoled Boots
Wand:
Ring:
Athame:
Amulet:
Pet:
Deck:
Level 30+
Hat: Polar Ice Cap
Robe: Meowiarty's Robe of Ice
Boots: Sprockets' Shoes of Ideals
Wand: Staff of the Ice Wyvern
Ring:
Athame:
Amulet:
Pet:
Deck:
Level 35+
Robe: Yakedo's Rational Cloak
Boots: Youkai's Slippers
Wand:
Ring:
Athame:
Amulet:
Pet:
Deck:
Level 40+
Hat: Jade Oni's Cap
Robe: Death Oni's Tunic
Boots: Forest Spirit's Careful Boots
Wand: Plague Oni's Sapphire Blade
Ring:
Athame:
Amulet:
Pet:
Deck:
Level 45+
Robe: Snowflower Cloak
Boots: Avalanche's Frigid Boots
Wand: Longblade of the Homonculus
Ring:
Athame:
Amulet:
Pet:
Deck: Blackrock's Obsidian Deck
Level 50
Robe: Malistaire's Iceflame Tunic
Boot: Snowcrusher's Snowstompers
Wand: Longblade of the Homonculus
Ring: Gurtok Celsius Band
Athame: Gurtok Chillblade
Amulet:
Pet: Ice Colossus
Deck: Blackrock's Obsidian Deck
For max level wizards check this video