|by an unknown master|
Instead of attacking in a round, a character may try to block an attack. When blocking, apply a character’s STR bonus + Shield bonus to their AC.
A Block can only happen if you have a shield or a melee weapon equipped (primary or an offhand weapon).
So a buckler is great for that. It's light and cheap and if it doesn't give you any AC bonus, neither does it give you any duel weild penalties. And you use it when you need to block a hit. I like the picture in the article too. Those dudes are not just trading hats!