hmmm, I wouldn't say that's the case for Beast Tamer. The part the manga and anime covered was just the stint where he's rapidly building up the party. Then, it's not an issue with the early ones being weaker but that each member's ability is the most relevant at the time they join. After this point, the recruitment slows down immensely. I think Tina shows up/anime ends around chapter 80 and the next to join should be around the 300-400s. Instead, they go through training arcs with their parents and fight bigger and more powerful foes. They get better at using their abilities and it stops being about who brings the new ability for the situation.This is why i hate this kind of manga, somehow the first group of the main character friends is strong at the start but somehow become weak, like the beast tamer exiled from hero party, eiyuu kyoshitsu, or boruto and many more.
At least if she gonna lose show us at her best form first so it's understandable, not to this stupid reason, i think she have more battle experience after her journey with the mc to see through fein attack and if it even a real chanting i think he is strong enough to withstand it or even cancel it. Come on author-san
For Amiyu, it's something different. She's the hero but, put frankly, she's not special. She can do everything and do it better than most but she's not unique in anyway. It's probably natural for this kind of character to get overshadowed by anyone who's more trained or has more unique abilities because she's basic.