  In the framework of seesaw neutrino masses from heavy fermion triplets
$(\Sigma^+,\Sigma^0,\Sigma^-)$, the addition of a light fermion singlet $N$ and
a heavy scalar triplet $(\rho^+,\rho^0,\rho^-)$ has some important
consequences. The new particles are assumed to be odd under a new $Z_2$
symmetry which is only broken softly, both explicitly and spontaneously. With
$N-\Sigma^0$ mixing, freeze-in long-lived dark matter through Higgs decay
becomes possible. At the same time, the $W$ mass is shifted slightly upward, as
suggested by a recent precision measurement.
