  We calculate the one--loop contribution from the $H^+ W^- Z$ coupling to the
static electromagnetic properties of the W boson. Although this coupling is
absent at the tree--level in all Higgs--doublet models, it can be induced at
this order in models including Higgs--triplet representations. It is found that
the $H^+ W^- Z$ contribution can be as important as those arising from other
couplings including Higgs bosons, such as the standard model coupling WWH or
the two--Higgs--doublet model couplings $H^+ W^- \phi^0$ and $W W \phi^0$, with
$\phi^0=h$, $H$ and $A$.
