It took me 3 months and over 100 hours of farming Atmas to get my first weapon. After the patch I decided to test out the new drop rates. I farmed up TWO Atma sets in about 2 weeks through very casual play. The Atmas would drop at a rate of about 20%, with most dropping in 1 - 5 FATEs, and occasionally taking 10, 15, 20 to get.

Atmas drop WAY more frequently, and I plan on getting all my Relics an Atma set now.