Winter's Edge Greatsword 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 greatsword. Usable only by greatsword wielders.
— In-game description
All Wintersday wooden weapons have a wintery snowflake glow as well as a pulsing white branch design. The greatsword's branch design creeps down the wooden blade. A picture of the greatsword's glow can be seen here.