So pleased with the Relic paddle holster that I just ordered the appendix version. My FN 509 fits snugly into the holster and the retention works well. This is a very high quality unit and is quite compact. I would recommend this holster. A magnet inside would aid in retention, but is not a deal breaker for me.
Relic Series Paddle Holster
I was having a hard time finding a good paddle holster for my FNX-9 and decided to try the Relic. It works great and I like the leather lining for smooth draw and the protection it provides for the slide and frame. I also purchased one for my Sig P320. Both fit the guns perfectly providing good retention while still easy to draw.