I was thinking to start for first time Diablo 2 classic and i wanted to know if there is any unique item on classic that gives % damage reduction!

no

just 10% on armor

Rockfleece but it sucks

Classic pvm is fun though and more of a challenge imo

If play classic, East or Asia

Block is "free" in classic (does not require dex), so items like Twitchthroe (+25% block) are big.