  Using the Schwinger boson spin representation, we reveal a new aspect to the
physics of a partially screened magnetic moment in a metal, as described by the
spin $S$ Kondo model. We show that the residual ferromagnetic interaction
between a partially screened spin and the electron sea destabilizes the Landau
Fermi liquid, forming a singular Fermi liquid with a $1/ (T \ln ^{4}
(T_{K}/T))$ divergence in the low temperature specific heat coefficient
$C_{V}/T$. A magnetic field $B$ tunes this system back into Landau Fermi liquid
with a Fermi temperature proportional to $B \ln^2 (T_K/B)$. We discuss a
possible link with field-tuned quantum criticality in heavy electron materials.
