At the moment, Jingyi's brain is made of distractions (ooh, Umbreon!) and rock music, and he is perhaps...less than careful. His center of balance did not change, but with so much less mass he has more oomph using the same about of spiritual energy. Which ends up meaning that when he tries to do his braking maneuver, he nearly kickflips himself off his sword backward.

He does not fall off his sword; instead, he pinballs through the crowd, bounces from someone's hip, and whallops into Null for a hard landing. His sword goes...somewhere. Flying a ways without him.

For Jingyi's part, though, he just flops backward off of Null onto the grass to stare up at the sky.

"That might have been a mistake," he tells Gladion in between pants.