Why was the government weak under the articles of confederation apex?

The government was weak for two reasons: one, the central government did not have the power to tax (raise money) and two, all thirteen colonies had to unanimously approve all legislation.

no, to many things have came in to factor

"a government in which power is divided between state and national levels". federalism is a system of government in which entities such and state and province, share power with the national government.