Unweaver adds
2PC +stamina
3PC +stamina
4PC +spell crit
...it is a LIGHT armor set
Infiltrator adds
2PC +magicka
3PC +magicka
4PC +weapon crit
...it is a MEDIUM armor set
It's sets like these that make you wonder a designer's thought process. If there is some sweet setup that I'm missing that benefits from these sets being the way they are, please divulge.
I can't see how they would be overpowered if set the right way; right meaning with more logical stats put together.
There are other sets out there that need to be reconsidered as well, these two have just recently come to mind with a build I was testing.