Complex sentence: He originally dismissed this weapon as a novelty, but he soon learned that it was capable of wiping out the Takeda cavalry; and he sensed that the arrival of the rifle in common warfare would put him out of business.
Split into simpler sentences: He originally dismissed this weapon as a novelty, but he soon learned that it was capable of wiping out the Takeda cavalry. He sensed that the arrival of the rifle in common warfare would put him out of business.