We were told that via patch notes http://pso2.com/news/announcements/valentines2021

That obliance series will become available after february 3. I have checked the exchange shop for divide medals but no sign of the obliance series.

Could someone shed some light regarding these weapons?

I hope it will be implemented in the next maintenance.

Yup. Maybe they'll fix this in the maintenance tomorrow. More speculations found in the following thread.

https://forum.pso2.com/topic/10353/where-is-the-obliance-series