I said at work once that someone twatted someone. And they were all
do you know what that means? And I said yes, but where I'm from, it means hitting/ punching.
That doesn't get away from the fact that twat general means cunt but less impact (except for a pp who said twat was worse than cunt where they are).
The thing about slut/ slag. Is interesting. They relate (these days) to being promiscuous. For years there's been a lot of stuff saying it's ok for women to enjoy sex, have sex with different partners of it's safe sex etc. I mean that goes back decades.
The 'slut walks' were about trying to reclaim the word. A pp said let's reclaim the word cunt! Like gay people did with queer.
But. It's not the same is it. The social context is different. Entirely. As shown by the fact that 60 (?) years after the 'sexual revolution' women on here still feel viscerally insulted by words like slut and slag.
I can't see in society here let alone around the world, saying hey I'm a slut, get over it. Will get us anywhere. I don't want to 'reclaim' them. I want them gone. I called my dad a slag once. He was. He was utterly shocked 
And the fact that cunt is still in many areas the worst thing to call someone in relevant.
Because it links into a load of stuff - from religions. From men. That cunts are still unmentionable. This is the reason there is no 'friendly' term like Willy.
The whole thing points to still a deep societal, erm. Discomfort? With female sexuality, biology, functions etc.