Dedicated cutting blades are wide and thin, and often have grooves known as fullers which lighten the blade at the cost of some of the blade's stiffness. The edges of a cutting sword are almost parallel. Blades oriented for the thrust have thicker blades, sometimes with a distinct midrib for increased stiffness, with a strong taper and an acute point. The geometry of a cutting sword blade allows for acute edge angles. An edge with an acuter angle is more inclined to degrade quickly in combat situations than an edge with a more obtuse angle. Also, an acute edge angle is not the primary factor of a blade's sharpness.