We conduct a comparative analysis of the mechanical response of a moderately fragile sodium borate melt, juxtaposing the adiabatic complex modulus measured at GHz frequencies using Brillouin light scattering and the steady-state shear viscosity measured at zero Hz. The two data sets are perfectly compatible with one another by fitting both components of the high-frequency complex modulus using a modified Maxwell-Wiechert model, transforming the loss modulus to viscosity, and extrapolating to zero frequency. This procedure yields an excellent fit to the steady-state viscosity under the condition that the static and relaxational moduli, as well as the activation energy for viscous dissipation are temperature dependent, as modulated by the logistic function, which accounts for the structural changes in the material as it transitions from liquid to glass. Accordingly, fragility of a glass forming liquid can be regarded as a measure of the rate of change with temperature in the energy landscape topography. • Modified Maxwell-Wiechert model to describe viscoelasticity of glass forming liquids. • Brillouin light scattering yields viscosity consistent with steady state viscometry. • Probed at high frequency relaxation peaks are better dispersed on temperature scale. • Non-Arrhenius viscosity behavior due to energy landscape changing with temperature.