  Branching ratios observed for $D$ and B decays to final states
$a_1(1260)^{\pm} X$ are comparable to those for corresponding decays to
$\pi^{\pm} X$ and $\rho^{\pm} X$ and much larger than those for all other
decays. Implications are discussed of a "vector-dominance model" in which a $W$
is produced and immediately turns into an axial vector, vector or pseudoscalar
meson. Data for decays to all such final states are shown to have large
branching ratios and satisfy universality relations. Upper limits on small
strong phase differences between amplitudes relevant to CP violation models are
obtained from analysis of the predicted and observed suppression of $B^o$
decays into neutral final states $\pi^o X^o$, $\rho^oX^o$ and $a_1^o X^o$. .
Branching ratios of $\approx 1%$ are predicted for the as yet unobserved
presence of the $D_{s1}(2536)$ charmed-strange axial vector in B decays.
