Throughout The Legend of Korra, there were so many skilled Benders introduced that the talents of some were only ever seen in snapshots and a scant few fights. While Team Avatar may have been in a new brawl every episode, characters like Avatar Aang's daughter Kya often fell to the wayside, only having a few moments to prove what they could do. But those moments are more than enough for some fans to claim she and characters like her are just as deserving of the status of a master-level Bender.
But not everybody can be on top. In order for Avatar to showcase a full range of talent, there need to be characters who are the best, characters, who are the worst and characters who are somewhere in between. Kya fits firmly into that last category, and that's for the better.
In the original series, Avatar: The Last Airbender, the main cast was made up of some of the best Benders in the world, with their only real competition being the White Lotus masters that helped show what top-level Benders could look like. The sequel series, Korra, expanded the cast to include even more characters while focusing on a far wider range of abilities and proficiency in fighting. The Waterbender Kya, introduced in Book Two primarily as a supporting cast member, provides a perfect example of a character who can excel in areas other than fighting.
Trained by her mother Katara, Kya was considered one of the best healers in the world and used those abilities to help save Jinora's spirit when she was under threat from Unalaq. Indeed, even apart from her bending skills, Kya was a valuable source of sage advice, easing the edge of her brother Tenzin's harsh personality and quelling family conflicts with her easygoing personality. Throughout the series, there were really only two fights she participated in and, considering that she was beaten in both of them, it would be difficult to make the case that she is a top-tier Bender worthy of ranking among the best of the best. And yet it still happens among the fandom.
The phrase most often used in Kya's showings against the Red Lotus is that her ability to "hold her own" in fights that she lost showcases those top-tier talents, and to a degree that is certainly reasonable. She faced off against Zaheer on her own, cornering him to a point where he tried to flee. When she went toe-to-toe with him, she certainly lasted longer than the White Lotus guards he dispatched easily throughout the series. In her later battle alongside her brother Bumi against Ming-Hua and Ghazan, she did much the same, though was ultimately overwhelmed by their attacks and thrown off a cliff.
As admirable as those showings are, however, it doesn't bode well for ranking Avatar fighters if anybody who can briefly fight a master Bender are themselves considered a master. If Kya's performance alone against Zaheer justifies her mastery, then what would that make Tenzin, given his own ability to overcome Zaheer in a solo confrontation? Avatar's world is a much richer and more complex place if the Benders that inhabit it range across a whole spectrum of proficiency in their talents. A binary between "bad" and "master" is overly simplistic and reductive to a world so rich in variety in other ways. When Kya has so much else going for her, it is gilding the lily to try to also claim that she is one of Korra's best fighters.
Kya's character works amazingly well for the supporting cast, and even past the series' ending, she provided a valuable heart-to-heart with Korra when it came to the characters discussing their sexuality. Such a topic until then was largely relegated to fandom guessing, but out of Kya's mouth, it felt so natural it fit perfectly within the Avatar world. With so much focus on Tenzin's family in the series, Kya represents a wise and easygoing voice found nowhere else among the family.
There is no real reason for her to be some hardnosed fighter, and if combat were really such a core aspect of her character, it would only seem odd that she was so uninvolved in the action of the rest of the series. Seeing herself as a healer and capable emotional support to those around her, it makes sense that Kya would only really fight when necessary and resign herself to other roles offscreen. So the next time the question of Kya's skill comes up and the argument about how good she is for "holding her own" against the Red Lotus rears its head, consider the wider problems her mastery brings. She's simply not the best, and that's OK.