Diablo 1 HD Hellfire Mod | Awake

I tried looking up what shield damage does but had no luck in finding anything.

For example, let's say the "Deflector Buckler" has a shield damage of 4-6. What exactly does that mean?

Thanks!

It's a dmg used when hitting with just a shield, without weapon equipped. You won't ever used it really, probably by chance if your weapon breaks during a fight and you'll notice using the shield attack animation once or twice, it's best to just repair the weapon than keep on fighting.

Otherwise don't use shilds like that

Thank you very much!