Following on from Keith's comment and the Northern California Sword Club link information these yari photos are from a newsletter from a Japanese sword dealer. I thought the difference between them was striking. They are almost different weapons so perhaps they would have been used differently and the training for them might have been different. The first one is a Jumonji-yari in the shape of a cross - which might have posed challenges in forging? The cutting edge is 25.6 cm. The second one is an O-mi yari with a straight triangular blade. The cutting edge is 57.2 cm.