When she realized that shoving Diamond to the ropes was impossible, because of both his superior strength and the traction-less floor, Rarity flared her stance and focused on constricting his windpipe. Her position was superior, her hold tighter than his, but his unbreakable neck and natural earth pony resilience was giving her trouble. She might be able to finish him with just this standing guillotine choke, but it would take a while. She needed an extra edge.