8. Upon each and every of the following objects and occupations the aldermen may, at [their] discretion, impose the following taxes, which shall empower them to ply their trade for one year, to-wit: […] upon every person, firm or company selling pistols, bowie-knives, dirks, sling-shots, brass knuckles or other like deadly weapons. in addition to all other taxes, a license tax not exceeding fifty dollars.