The jet boots weapon action turns a PA in progress into its alternate version, and is a very useful tool for getting the most of of your jet-boots Bouncer. Strike Gust's normal mode is to kick upward into the air. Strike Gust's weapon action reverses that, quickly grounding you and creating a shockwave and the Shifta effect where you land. Grand Wave is a charging attack. It sends you forward to deliver several kicks into the enemy you collide with. The weapon action reverses that to send you spinning directly away from the enemy you targeted (or auto-targeted). The spinning away is a full second of I-frames, meaning you can't be hit during it. If timed right will allow you to survive a lot of stuff that would deal serious damage to everyone else. The Deband effect gets activated the moment the weapon action gets used, at the location it's used. Surging Gale can cast Zanverse as part of the weapon action as well. The normal action kicks 4 times left and right to do AoE damage, while the weapon action alters the attack into a spin that draws enemies in, deals a lot of smaller ticks of damage, and casts Zanverse while spinning.
To figure out what's going on, you may need to drag your friend into the Damage Practice: Rockbear training and watch what is happening.
The Shifta, Deband, and Zanverse used is at the level learned and modified by the custom disks learned. So your friend should be able to slot Shifta and Deband to the sub-palate or a weapon and use them directly. The weapon actions doesn't need the techniques to be slotted, but if the option isn't there then he hasn't actually leaned the techniques properly.
If he can cast the techniques directly, look at him use the photon arts and weapon actions. With Strike Gust, if he spins in the air and kicks, or just spins in the air, he isn't using the weapon action properly and needs practice. The proper weapon action will slam into the ground while activating Shifta. That is similar with Surging Gale. If he doesn't spin backwards after charging forward, he isn't using the weapon action, and needs practice. The Deband auto-cast also sends the Bouncer spinning backward for a second (which can be canceled with another technique, photon art, dodge, or attack).
If he is able to make a ground-slam with Strike Gust or spin backward after a Surging Gale, but not generating a Shifta or Deband then the only thing I can think of is that the techniques aren't actually learned. Start over and make sure that he can cast Shifta and Deband directly.
Hope this helps.