My DRK weapon is giving me the same issue. I unlocked 5 lines on augmentation on PLD Sword in 7 tries, PLD Shield and WAR Axe in 6 tries. On 8 rolls on my DRK Greatsword and also still at 2 lines. I haven't been motivated to go back in to Pyros this week because I finally got the mount from Bunnies and I was also really close to getting some other mounts from achievements so I decided to focus on those instead.