We present weak-lensing analysis of 22 high-redshift clusters based on HST/ACS images. Most clusters in our sample, providing significant lensing signals, are well detected in their individually reconstructed two-dimensional mass maps. Combining the current results and our previous weak-lensing studies of other  high-z clusters, we compare gravitational lensing masses of these clusters with other mass observables and also examine their theoretical probability of existence using the standard structure formation paradigm. The lensing results are in good agreement with dynamical velocity dispersion measurements and X-ray data. For the first time, we establish lensing mass-temperature relation at z>1. For massive clusters, the relation is tight, and the power law slope is highly consistent with the theoretical prediction. Considering their predicted abundances, we find that the discoveries of the most massive clusters in our sample are highly improbable even when we conservatively assume  300 sq. degrees for their search volumes and marginalize over the lensing measurement uncertainties. We will discuss some cosmological implications from these results.