I (personally) don't think the leg shifting back adds anything to the animation. Regardless of what I think, it's nicely done overall.
^ I mostly agree with this.
I think the leg snap looks funny and unrealistic... I'm 100% sure Lucina's ankle just broke there... Naoto's animation seems slightly better because the foot doesn't become parallel to the shin, so it looks a bit more realistic.
Still, I think putting your knee to the ground may help you extending your reach for the last sword hit, but it doesn't help you AT ALL in getting back to a standing position.
In a real life sword fight situation, it would be a chance decision: lean on your knee to extend your reach, while making it harder to get back to standing up, to maybe land a decisive blow, but maybe if that fails, it would leave you open while trying to get up from the floor.
Maybe to understand what I mean, you'd need to try doing this movement in real life (with an umbrella as the sword xD)
You may keep your animation as it is, just keep this in mind.
Wait1 is very solid. Wait2's feet are a bit shaky, but overall it's great.
Actually, it's not just the feet, but the legs. Notice how they move closer the moment he raises his arm, and also when he lowers it (more noticeable at the knees). Might want to take a look at the keyframes.