  We present the weak lensing analysis of the Wide-Field Imager SZ Cluster of
galaxy (WISCy) sample, a set of 12 clusters of galaxies selected for their
Sunyaev-Zel'dovich (SZ) effect. After developing new and improved methods for
background selection and determination of geometric lensing scaling factors
from absolute multi-band photometry in cluster fields, we compare the weak
lensing mass estimate with public X-ray and SZ data. We find consistency with
hydrostatic X-ray masses with no significant bias, no mass dependent bias and
less than 20% intrinsic scatter and constrain fgas,500c=0.128+0.029-0.023. We
independently calibrate the South Pole Telescope significance-mass relation and
find consistency with previous results. The comparison of weak lensing mass and
Planck Compton parameters, whether extracted self-consistently with a
mass-observable relation (MOR) or using X-ray prior information on cluster
size, shows significant discrepancies. The deviations from the MOR strongly
correlate with cluster mass and redshift. This could be explained either by a
significantly shallower than expected slope of Compton decrement versus mass
and a corresponding problem in the previous X-ray based mass calibration, or a
size or redshift dependent bias in SZ signal extraction.
