A ring R has weakly stable range one provided that aR+bR=R implies that there exists a $y{in}R$ such that $a+by{in}R$ is right or left invertible. We prove, in this paper, that every regular element in an exchange ring having weakly stable range one is the sum of an idempotent and a weak unit. This generalize the corresponding result of one-sided unit-regular ring. Extensions of power comparability and power cancellation are also studied.