The wide blade at the head with an indentation into the blade towards the hilt is designed to give more weight to the head of the blade, allowing for more momentum with slashes. Like a machete, it does bonus limb damage. It can be repaired with another machete gladius, or regular machetes. It has fairly high DPS due to its speed, which allows up to 3.5 regular attacks per second; combined with its 28 base damage, it readily cuts through most armored enemies.
It has a special 'Back Slash' attack, which does 70% damage in V.A.T.S. at the cost of 16 action points (requires a Melee skill of 50).
Despite sharing a name with the Roman Gladius, the blade doesn't look like one. It doesn't look like a machete either: the blade is makhaira, with more resemblance to a falcata or kukri.