Strongest duelist? My Olivie with 100% physical dodge says hi~~

And Sabinne is not a duelist mainly. It's the fact that she's a ranged dps from a melee slot. Sybilla can only do this during her skill and i recommend getting at least one full time melee ranged up because they'll become more and more important. Sabinne also deals true damage if you ever care to SAW her once that pops up.

That said, Sybilla to AW50 is at least a must, but closer to her max level the stats she gains are not that impressive and you generally want AW'd units to about 80% to get the most stats.

...also subjugation events in the future love being incredibly limited on ranged slots with the harshest i've been on having only 3 ranged slots.