It seems we have some very different ideas on how to kit Nalili out, heh

As nice as the Tormented Shield is for her, I prefer to give her a Buttplug to preserve her Lust and give the shield to Simon. Mind you, Carina's pretty much a perma-include in my party so I don't really prioritize defence on other characters. As long as they can survive the first one or two hits from the baddies, we're usually set.
I did that once, too. Works decently well, but after you've played through the game a few times already, you kinda start preffering a combat team that can kill things, before you ever have to go on the defensive. Takes half the time.
You may be surprised that Simon makes for a surprisingly capable healer after he gets the Incubus Glove, which invalidates the need for Carina in regular foe encounters. Support Allies can heal several thousands of HP to your entire party, and other members of the party can fill Tormented Shield-Simon's attacking role more effectively in damage per turn.
Try facing some normal groups of foes with Glove-Simon and 3 pure attackers like Robin, Riala, Varia, Aka or ATK-specialized Uyae. You might be surprised at it's effectiveness for most dungeons in the game.
BP is admitedly a fantastic item, and I never let Yarra or Qum go without it. But BP Nalili just ends up as an inferior Varia or Aka when using it, in my experience, which removes any niches she might have in your party. With the shield she becomes an excellent choice for bosses or encounters where you know it will last for some turns. She spends one turn on setting up, but afterwards she hits harder, faster and is very hard to kill.
That's just my take(s) though. Truthfully, the game balancing in TLS is remarkably underrated and there are so many viable ways to make use of the same characters through different equipment and party combinations. Everyone has a potential role.