Dusk Elf Stealth is an elf bloodline feat, introduced in Dragon Magazine 382, to represent a character as a Dusk Elf. [Dr382:68]
When an elf selects this feat, all allies within 6 squares that do not likewise have this feat gain a +1 racial bonus to Stealth checks.
The Dusk Elf subrace is represented mechanically by selecting this feat. There is otherwise no difference to your character.