If somebody said to me "China emperor", I would visualise a ceramic statue of an emperor. That's only because china has more than one meaning and, without any context, the wrong meaning seems more probable.
It is possible to refer to a group of people who represent a country by the name of he country, for example you can talk about England, in the context of football, to mean the England football team. In the same context, you can say "the England manager" to mean the manager of the England football team.
This usage is not a possessive: it is a compound noun made up of England (meaning the group of people who represent England in football) and manager.
In the context of football, "the China manager" might be understood, but some people might still interpret this as another ceramic statue.
In a compound noun, the final noun is the main one and the preceding nouns act in an adjectival role. In the case of China, it would make more sense to use the appropriate real adjective Chinese, giving "the Chinese emperor". Again, this is not a possessive.
The England's king emissary.
This sounds like something that you might see in subtitles for a bootleg Asian copy of a DVD. Can you provide a link to it? The nearest grammatical phrase would be
The English King's emissary.
Moving on to "life force", this is a compound noun like "England manager". Again, it is not a possessive.