My 2 cents is that Lukhas is right nothing wrong with slice.
I use slice on 2nd serves sometimes on 1st serves especially when I am pulled wide. On 2nd serves I get in no man's land and slice an approach and take the net if its a soft serve. If its a kicker I'll take it early if I can.
But for 1st serves and 2nd serves too I mostly will use a sw or western forehand and as Lukhas says I dont have to switch grips, which IMHO is half the battle on a fast serve.
I am slow so I often hit open stance but can rip the ball if I can get to it or at least block it back with pace. In the ad court I can hit outright winners off a good serve mostly because I will be a bit late and that opens up down the line. On the deuce court it is fine too because that is the safest return over the low part of the net.
Not saying it is easy, extreme eastern and sw backhand grips arent exactly natural for most. I used to hit a normal eastern backhand. No way I could hit that now, its just not a natural stroke now, so there IS hope for you. But if you dont have a sw forehand or western forehand well just forget it and make your slice work better.
If you can hit either of those forehands, then if you are in the waiting position with the strings parallel to the ground and your non racket hand on the throat and finger on the strings, you can just pull your non racket arm back a bit, turn your hips and you are in position to block the ball back powerfully.
You might be able to do something similar with the regular eastern bh grip, but I can't advise on that, though picking up a racket it doesnt seem that it would be as strong as a sw or extreme eastern.
6.1 95 (18x20) customized to 380g with a 5 1/4" squarish grip
Ashaway Kevlar 17g/MonogutZX Pro 65/45lbs