You give Blind Snowman A Lump of Coal.
Blind Snowman tells you, "What's this?"
Blind Snowman tells you, "Wohoo! Thank you! I'll be able to make a new set of eyes once this gets cold enough!"
Blind Snowman tells you, "You deserve a reward for your good deed. Let's see... well not see per se... one second."
The Blind Snowman scoops up a pile of snow and casts a spell. The snow coalesces forming ice crystals that shift and rearrange as if alive.
Blind Snowman gives you Snowman Snowglobe.
Blind Snowman tells you, "I can't be sure it turned out exactly right, but I hope you like it."
Blind Snowman tells you, "May your bottom stay cold and your eyes stay put. Soon I'll be able to see the snow again!"
The Blind Snowman swallows the Lump of Coal with a contented smile.