Opinions, eh? Well do you remember
this post? Here is where I talk about two specific animations I like the least. But, here's the key point, I say
why I don't like them.
And the reasons I list are not opinions.
If a slash begins standing and horizontal, but ends with your sword pointed skyward and your knee on the ground, you have wasted part of your swing's force in the wrong direction. Kinetic force is best carried in a straight line, so if your line starts straight and then abruptly curves skyward while you curve groundward, you've just lost a lot of force.
That is not an opinion, that is an actual fact. The swing looks bad because it's obvious even at a casual glance that it was a poor swing; all style, no substance.
Vergil is falling straight down during helm breaker. The best way to carry the considerable force of a body dropping out of the sky would holding your sword directly below your center of mass (a straight line), not outstretched in front of you with a single arm so you end up on the ground like a tripod. Classic vergil's helm breaker keeps his legs from touching the ground until the last possible moment, hitting at nearly the same time as the tip of the sword makes contact with the ground. Reboot vergil lands straight legged on his toes, his body leaning forward at almost a 45 degree angle,
before his sword hits the ground. Most of the force is lost when the legs hit the ground, most of the rest is lost through angled distribution. Reboot vergil's helm breaker is ****.
That is not an opinion, that is a fact. It's called leverage,
and can easily be illustrated with vectors actually vector math isn't necessary. Even if you didn't trust the basic rules of leverage, you could prove it to yourself with creative use of trig (a highschool subject)
Two arms can pack a bigger punch than one arm. If vergil was really all about power and substance over style, he would belt the sheath, stop twirling, and hold his two-handed katana in two-hands. The hilt of yamato is over a foot long -- by dimensions yamato is a two-handed katana, not a
one handed cavalry katana.
That is not an opinion, that is a fact.