Guild Wars 2

I tested it with a friend who has Twilight, and found that Legendary footstep effects still display while in stealth, easily giving you away.

Not only that but they’re simply bad in general, making it much harder for you to escape foes by hiding in corners and around obstacles.

Can we please have an option to disable this graphic for our characters?

Good luck with that. With an estimated <5% of the player population being determined and willing to invest enough time to craft a Legendary I don’t believe “fixing” this will be high on Anets priority list. On the other hand Legendarys were not made for use in PvP or WvW. The purpose of Legendarys is to stand in Lions Arch all day showing to others how leet you are.
Enjoy the particle effects.

Are you sure they display to enemies? Were you standing next to your friend in Lion’s Arch or were you on opposing servers and standing next to him in WvW?