Question: Why is Weaving Harmful?
Answer: Weaving isn't generally thought of as a harmful or destructive habit. But, over time, prolonged or frequent weaving can cause uneven wear on the horse's hooves. Joints and muscles can be stressed by the repetitive motion.
The constant motion of weaving burns energy, so it is possible that these horses will also be difficult to keep at a healthy weight.
Weavers have been known to damage soft floor surfaces like sand or dirt floors. Commonly, a weaver will break down the flooring, usually in front of a door or other opening where they can hang their head over a stall partition. Outdoors, it's less likely a weaver will cause anything but minor damage.