At 4th level, a cavalier learns to train mounts with speed and unsurpassed expertise. The cavalier receives a bonus equal to 1/2 his cavalier level whenever he uses Handle Animal on an animal that serves as a mount. In addition, he can reduce the time needed to teach a mount a new trick or train a mount for a general purpose to 1 day per 1 week required by increasing the DC by +5. He can also train more than one mount at once, although each mount after the first adds +2 to the DC.
