Suggested by Sonic Sephiroth is incredibly fast and may surpass Accelerator in that area. You can barely even react to Sephiroth swinging his sword, but beyond that Sephiroth’s ranged attacks will be less useful here since Accelerator can reflect them all. Accelerator was pretty limited for a time when he needed the network to connect, but on his own he can use his abilities without worry and for a long time. I don’t believe Sephiroth will be able to keep up and since one touch from Accelerator can mean death Sephiroth can’t afford even the slightest mistake. Accelerator wins.