Static electricity and door handles

When discharging without a tool, the whole charge exits your body through a small skin surface area, say $0.1$ mm$^2$.

When you hold a tool that surface is much bigger; perhaps $100$ cm$^2=10,000$ mm$^2$.

That means that the current flowing through neurons in that area is much lower, and perhaps low enough as to not be felt.

Pretty much the equivalent of spreading the same electric current through $100,000$ cables instead of $1$.