Clubs +1 are added in BG:EE in order to increase the array of clubs in Baldur's Gate, as the only club in Baldur's Gate which existed was the standard club. Krumm in the Dryad Falls area east of Gnoll Stronghold drops one.
From chair legs to felled trees, clubs are the universal weapons of everyone from tavern brawlers to hill giants. A little extra weight, maybe a spike or two, and a little enchantment never hurt. Which is to say, it always hurts.