The tax probably originated in a tribute levied by a conqueror or ruler upon his subjects, and perhaps the custom of dedicating a tenth of the spoils of war to the gods led to the religious extension of the term, the original offerings to deity being "firstfruits."
KoXeos ("sword-sheath"); and Xacipia (see above) may refer to the spoils of war as well as the chase.
Does he grow rich on the spoils of war?