Depends, how sharp were the corners before twist? If they were a little rounded off, and they are not standing out real sharp after twisting, it is likely that you can just forge the bar square, or directly into a blade.
Just keep an eye on whether it looks as if the lows are getting forged too far down into the billet surface. If you think that's happening, grinding would be the correct response.
Also, you'll want to leave the forging thick anyway so you can grind down into the pretty of the pattern...