he uses his shield quite often if I remember correctly. In the first part the objective is to destroy the flying lanterns that shoot laser rays and to knock the spider arachnero off his perch.

When he finally comes down to earth and does his smoke disappearing act use your special ... as the beast you can throw fireballs with more of an impact. Still arachnero is only vulnerable when his shield is down and wings spread wide.. If he can fire at you/ you should be able to connect back.

Shoot too soon or too late you have to wait again until the next opportunity
Timing is everything in this part not how much ammo you have ..