In the dream I was playing some game that was supposed to be released just before Metal Gear Rising, and Metal Gear Rising was the sequel I guess. I was playing as Raiden with the high frequency blade. Unlike Metal Gear Rising, it didn't have the blade mode where you can slice stuff up however you want. Instead, you had to hold down the attack button to charge the attack, and releasing it would do a slice that cut things in half.
The attacks were otherwise very fast, and the charge attack was glitchy and sometimes didn't charge or whatever.
Twas good.