Some of the stuff you're into definitely would not feel good to the person you're subjecting it to. Like stinging them with jellyfish or pistol whipping them. That would seriously injure or even disfigure them, Jay.
This.
It's not wrong to be a sadist, it's not heinous to be into kink.
But as someone in the kink community, I have some valid advice for you on this as well.
Kink shouldn't seriously injure or disfigure. I honestly think a lot of your fantasies are just that, fantasies. The reality of a girl screaming from legitimate hurt during a cattle prod session would probably not be all that hot outside of fantasy, or at least I would hope.
As a sadist, you should be in touch with your empathy, you should not want to seriously harm your partner. You should want it to give them some satisfaction too.
Without getting too TMI, I am quite familiar with this type of play. But spankings, light hiting, and electrical play with the proper toys are quite a far cry from things that could seriously disfigure, and even so, I am very careful. I am constantly checking to make sure my partner is not saying the safe word or visibly distressed.
Please try and take the time to separate your fantasy from reality. In fact, anything you want to do to a partner, it is quite possibly a good idea to find a way to try on yourself first, to make sure it won't really harm anyone in consensual play.