  Recent theoretical proposals have argued that cobaltates with edge-sharing
octahedral coordination can have significant bond-dependent exchange couplings
thus offering a platform in 3$d$ ions for such physics beyond the much-explored
realizations in 4$d$ and 5$d$ materials. Here we present high-resolution
inelastic neutron scattering data within the magnetically ordered phase of the
stacked honeycomb magnet CoTiO$_3$ revealing the presence of a finite energy
gap and demonstrate that this implies the presence of bond-dependent
anisotropic couplings. We also show through an extensive theoretical analysis
that the gap further implies the existence of a quantum order-by-disorder
mechanism that, in this material, crucially involves virtual crystal field
fluctuations. Our data also provide an experimental observation of a universal
winding of the scattering intensity in angular scans around linear
band-touching points for both magnons and dispersive spin-orbit excitons, which
is directly related to the non-trivial topology of the quasiparticle
wavefunction in momentum space near nodal points.
