"Ou pa konn sa m peze' seems to have nothing to do with weight or scale. am i right? if yes, what does it mean then?

Most likely it does not.  And you're probably asking because you realized that if you translated as "weight ....and such" it would not fit into whatever you're reading.
If this is the case, then it means "you do not know my strength /what I can do/ who you're dealing with/ etc..."
Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words