Could this be the live action Fullmetal Alchemist movie?
Live-Action Dystopian Cyberpunk(?) Sci-fi movie/show
It is set in an alternative present where alchemy is a well developed science, so there are both familiar technologies like trains and people with magic-like powers.
It might have been several years ago.
It was released at the end of 2017, which may or may not match your definition.
Many people seem to have bionic parts of some kind.
The main character, Edward Elric, has a mechanical arm and leg (this kind of prostheses are named "automail" and are a well-known technology in that world, so other people could have some too), while his brother Alphonse is an empty suit of armor (it's complicated ...).
One woman is interrogating another woman sitting across from her. Suddenly, the interrogator's boot/shoe turns into a terrifying, large black spike. She lifts her leg and impales the other women in the stomach with it.
This might not match perfectly, but is similar to what you remember.
One of the villains is an homunculus named Lust having the appearance of a beatiful woman; her fingers can turn into long sharp black claws.
I haven't watched the movie, and it has been a long time since I watched the animated series, so I don't know whether she can turn her feet into weapons too.
The movie poster shows her in the top center position, together with many other characters.
The IMDB Fullmetal Alchemist image gallery contains a lot of stills, so you can check if this is the movie you were looking for.