Liguy,
that was my quote, just FYI.
as you correctly alluded: slew rate & bandwidth are related.
You also know that Q=i*t=V*C. so, V/t = I/C. So, slew rate can also be spec'd in terms of how much current into charging/discharging a capacitor.
Damping factor is an indirect measure of the amp's output impedance.
Needless to say, if an amp has higher output impedance (i.e. low DF) then it's more unlikely to supply higher current into the load (as most will be dissipated as heat).
So, there is a relationship between the two.