I have to admit I'm a little disappointed that Bern appears to have to go through basically no character growth so far. She just sort of gets handed magic weapons that will let her win the fight.
I'm reserving total judgement until I see how this plays out, but I think this particular arc has left a lot to be desired so far.
I remember in college, a guy from my drama class was convinced that if a character wasn't completely different, the writer hadn't done their job. I wasn't sure I agreed. Now I know I don't.
A character can be made one-dimensional (that character is "evil/good", that character is their job title like a guard or smith, that character is pretty/ugly, basically they can be summed up in a single word) or flat, two-dimensional or have personality (basically you choose a list of traits, and the character is basically the sum of their traits), or three-dimensional (they act like a real person you would meet on the street rather than a persona, they have flaws, they have pain, they may have addictions or moments of darkness) and "well-rounded". Now, being one-dimensional isn't always a bad thing provided the character is minor, likewise, a story is said to be really good if minor characters are at least two dimensional. Likewise, unless you are doing a melodrama, the hero of the story should not come across as one-dimensional, as people will accuse you of bad writing.
Among fully fleshed out characters, there are two distinct and equally valuable character types. The static character and the dynamic character.
The static character, despite their name, actually can undergo character development along the course of the series, but they tend not to. That is, a static character has character development as an optional feature. Bern is a static character. A good example of this tye would be Naruto, he spends over half the show talking about how he won't take back his words, that is his ninja way. Character development on his part is extremely subtle, and he simply adds character rather than changing any of his current ways (he still won't do this or that because of his ninja way, but gradually learns to trust his comrades and not try to do everything himself).
The dynamic character, undergoes character development frequently, changing gradually from one person to another. They are not afraid to let go things that aren't working for them, and massively revamp their personality. Maytag is a good example as she started out deadpan, and then became the mask, and is expected to change even more. A good anime example of this is Luke from Tales of the Abyss, starting out as a nice jerk, becoming just a jerk, realizing the error of his ways, then he finds out he's a clone, then gradually becomes a proper hero.
I guess it's fair to just assume that beambro is a seasoned veteran and wouldn't do such a rookie mistake just like we just accept that the "split rose" is the "ultimate defense technique" even though it probably doesn't make much sense in a real fight in which lots of sword "clang clang" never really happens.
Do we in fact know this? Maybe he's a person who has gotten by on a heavy weapon and using gravity-self magic. Sort of like if you have wolverine-style healing, and something hits you that can't be healed, you wouldn't normally be good at dodging, because you would be expecting to shrug it off (wolverine, oddly enough being an exception, because despite being night-immortal is also a seasoned fighter). Bern on the other hand, has had plenty of experience in all types of combat, and knows when to get out of the way and when to try to block. She uses a style that requires studying the enemy rather than just slashing people down. It seems to me, that she is the seasoned warrior, he's just a big thug with a big sword. Especially given that his attacks leave openings all over the place, and after being blocked, his first instinct is to just do a big overwhelming downswing. Oh yea, the other stuff worked so well, let's try the same tactic. If he was a seasoned warrior, he would try to disrupt her balance by attacking the ground or something (we know the sword can disrupt direct attacks, but maybe not shock waves or indirect stuff).
I was thinking this as well, but the problem is, that sword isn't a tiny bokken, so any feint would require teamwork with the others.