These dropped for my group off of High Priestess Sercema, a timed spawn in the siren tower. She has no PH, just pops every 2 days i beleive. Conned blue to me at 65, was an easy kill once the tower mobs were dealt with to prevent adds. Killed her twice, dropped these arms and a random velious armor BP gem both times (got a pristine emerald the first time, and a flawless diamond the second).
Gratz to my pal Zayur on his new arms (the ranger in the screenshot) and to Bloodchiller who won the second pair at /ran after no one needed them as an upgrade. Good luck to anyone else who goes after them.