Rating pool

It seems that rating here doesn't mean much. I am 1550 at standard live and I yet am better than 92,3 % players in the pool. At another site I had standard live rating 1850 and still I was better than 90% of players. So I conclude that someone who has standard rating 1600 isn't a weak player at all ? Right ?

 1600 is class B.....they are obviously strong tournament players.  Of course though, rating is relative and different sites have different methodology and opponent pools.

Weak is relative. A 1550 rating here is MUCH better than a beginner. I imagine you've learned a lot about chess and played at least a few years. The average active OTB club player is something around 1600. Even though chess.com rating isn't the same as OTB you're doing well, good job.

Some people will consider 1600 weak though. In chess, as we improve, what used to be new and difficult knowledge or skills become second nature to the point we don't even realize we're doing them. So some people will consider 1600 basically clueless... and some pros consider weak GMs basically clueless  Like I said, it's all relative, and in reality you've learned / improve a lot from the time you were a beginner.