The Buckler is a Shield for the Tank. This shield, like all shields, are used with a Secondary Weapon. The Buckler, like all non-reflective shields, (due to an unpatched bug) increases accuracy rather than decreasing it. It only suppresses 20% of damage however, and it is surpassed by the Meat and the Blast shield.
Although the Buckler increases accuracy when crouching, all other shields that do not reflect attacks also increase accuracy due to what seems like a bug, making the Buckler inferior to the Meat or the Blastshields.
A Buckler is a Medieval shield made from leather and wood. It was later replaced by more reliable and sturdier equipment.