Winter's Needle Dagger Skin
From Guild Wars 2 Wiki
“Double-click to consume.
Seasonal. For sale only during the Wintersday season. Use anytime to upgrade the appearance of a dagger. Usable only by dagger wielders.
— In-game description
All Wintersday wooden weapons have a wintery snowflake glow as well as a pulsing white branch design. The dagger's design blends branches and snowflakes below the dagger's hilt. A picture of the dagger's glow can be seen here.