Personally, I kinda liked Sela in "Redemption". In that scene with Picard, there were some stong hints of "internal conflict". Note how worked up she gets when she tells the captain how SHE betrayed her mother to her death. It seems, to me at least, as if the ghost of her mother has been tormenting her since her death...and Sela's trying to justify what happened--to herself, as well as Picard.
It also seems like she's trying to get some kind of reaction from Picard, when she says, "All that's left in me is Romulan--NEVER DOUBT THAT!"
When Picard shrugs it off, Sela looks a little stung....
Anyway, her stint in "Unification" seemed rather simplistic in comparison. It seems like the writers just brought her in as a plot point--probably, they intended to make her a reocurring villian like Tomalak, or the Duras Sisters, but apparently, nothing came of that....
"The saying implies but does not name the effective agency of its supposed utopia.... 'Needs and abilities' are, of course, subjective. So the operative statement may be reduced to 'the State shall take, the State shall give'."