There is a bug where no matter how much power strength you put on Ash his shurikens not only not show it in the UI but it does not affect its damage.

Here is a post about it.

https://forums.warframe.com/topic/1217940-fix-ashs-shuriken-bug/

If anyone feels the same way about DE fix his shuriken bug please show support, flood the bug section with this issue and leave a like on this post.