From the October 15th update: “Signets: Signet passive buffs are now properly applied upon entering a PvP map.”
This is not the case at all. It still behaves like before, needing to be activated or re-equipped in order to work (or water entry on Capricorn). This is quite annoying for signets and guardian virtues.
Josre
Zulu Ox Tactics [zulu]