Arcana and History. Your expertise lends you additional insight when examining metal objects, such as weapons.
Investigation. You can spot clues and make deductions that others might overlook when an investigation involves armor, weapons, or other metalwork.
Repair. With access to your tools and an open flame hot enough to make metal pliable, you can restore 10 hit points to a damaged metal object for each hour of work.
Additional uses. You can use your smith's tools to do a variety of things, as your DM if you may use the tools for a specific task. Examples of such tasks are as follows; Sharpen a dull blade, repair a suit of armor, sunder a nonmagical metal object.