I do not know if this is intended behavior or not, but if a thief is in stealth and uses SB 5, the animation for the Infiltrator’s Arrow still is visible. This make is a bit pointless to be in stealth in PvP or WvW if weapon animations are visible. I first noticed it in WvW tracking a thief and tested it in PvP.
See attached videos.
Regular SB: https://youtu.be/wFs-KrxfY5o
Legendary SB: https://youtu.be/vPGNr2GmIPM