I haven’t watched that episode in a looooong time, so I can’t really contribute too much to the conversation. But the vibe I got (and I may be misremembering) was that Sisko was trying to let her know she could be that person, if she wanted to be. She could be Fenna, because she was Fenna. A sort of “the [Fenna] was in you all along” type moment.
I’m mainly posting here because DS9 is my absolute favorite series (close second is ENT), and I’ll happily contribute to any ds9 talks. Lol. Is there a community for ds9? I haven’t found out, but that could just be lemmy search shenanigans.