Lothern Sea Helms

Sea Helms are the greatest heroes of Lothern, an order founded in the time of Bel Shanaar. With both spear and bow they have perfected the quicksilver strike that cheats shields and parries to pierce throats, hearts or skulls.

Sea Helms often take their place amongst the ranks of Lothern Sea Guard, so that their presence might inspire others to greatness. The Sea Helm's finely-honed instincts combine with the Sea Guard's discipline to create a force that can swiftly adapt to changing fortunes. However, most Sea Helms choose to fight from the back of a swift Lothern Skycutter, the better to dart through volleys of arrow and bolt, swoop into the heart of the foe and fell an enemy hero with a single strike. Such an attack takes great steadiness of nerve and spear-arm, but the Sea Helms have both aplently.

Source
Warhammer Armies: High Elves (8th Edition) -- pg. 43