[quote=@DarkwolfX37]
Right but I meant glaring things like exposed joints or something.
[/quote]

As I said, the Protectorate's engineers are actually not totally incompetent, so there won't be any glaringly obvious weak points like exposed joints. The humanoid PCUs can be assumed to have anatomical structures that are at least somewhat similar to a human's, so you could go for human weak points as an educated guess, but it's obviously not guaranteed to work.

Also, I should point out that [i]not[/i] all PCUs have very similar auras. The more developed ones have their own unique auras just like normal spirits, and the most developed ones even have their full individual personalities.

Edit: I rewrote section 2.1.8 of the Codex. Now it elaborates more on how a soul actually develops, and also states the limitations on creating souls.