It is never easy to select the best of a group. A test can be done to decide who are best and who aren't but it's not a simple matter as one would think.
What should the test base itself on?
Everyone has their own aptitude. They excel in something they like or have talent in. There is no definitive test to check the best of a group. There are only tests to verify if they are best in that particular category.
The situation is the same for Klaus here.
When the system informed him that everyone who took the awakening serum, would awaken but not in the way the world knew, he didn't understand that.
It wasn't until later he came to a conclusion that unlike this world's awakening platform, which only produces Mages and Knights, this serum would most probably do something different.
