Taking out playbooks felt big, but they just weren't adding anything. Instead I focused on including interesting and diverse abilities, and I already had sixteen distinct elements for four core traits, and every princess chooses a speciality anyway (Cookie Princess, Tiny Princess, Stabby Princess etc). I also had a good look at the territory/claims mechanic and eventually decided that for this game they could be replaced by a simpler system that flowed better with the other mechanics. Bit ironic seeing as this mechanic was one of the big initial draws to FitD as a base, but oh well.
I also added an escalation mechanic, influenced by 7th Sea's raises. Players can increase the number of sides of the dice they're rolling in exchange for increased effect. Being able to voluntarily raise the risk of a roll in exchange for increased effect has a feeling of drama and power that I really like. It feels very princess. I also wanted a mechanical representation of princess flamboyance--rolling d6s on an action means doing it in an efficient, conventional sort of way. Escalating to d8s or d10s or d12s or, hope bless you, d20s carries with it the chance of spectacular success, but also the risk of spectacular failure. This one feels like the biggest break from the pure core of Blades (those precious blessed ever-elusive 6s), but it works well in play and besides, I love having a chance to break out the polyhedrals once in a while.
There are a lot of smaller changes too, and honestly one of my favourite parts of designing this is getting into really pedantic examination of each mechanic, like 'what is this DOING, why is it HERE'. (And Blades in the Dark is such a nicely designed game, it was a joy to slowly pick it apart.) But, overall I was surprised at how well the mechanics for scoundrels doing crimes in a haunted fantasy-industrial city translate to a game about demigod-avatar princesses balancing tea parties and giant monster attacks.