Winter's Reach Longbow 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 longbow. Usable only by longbow wielders.
— In-game description
All Wintersday wooden weapons have a wintery snowflake glow as well as a pulsing white branch design. The longbow's branch design flows up and down the bow's body. A picture of the longbow's glow can be seen here.