A question about shinki action in battle

[Rinkun]

what is the possible cause for 敵の攻撃に備えるため回り込みます?
What does it actually do?
from my guess shinki use that to counter skill usage?like use a defence skill to guard a special attack.
but since i dont have any i find that action really useless so if someone can clear this up for me it will be great

[MaximumBurst]

I believe that action is linked to telling your Shinki to focus on evasion. When a Shinki does that sideways movement, its evasion increases a pretty significant amount. I *think* it's usually about 10%.

[Rinkun]

Another question iam trying to get my arnval to use her movement skill at the right time and just wondering is the reason she use it important?