Hexblade's firearm and medium armor mastery

You have practiced moving in medium armor and handling firearms to gain the following benefits:

• Wearing medium armor doesn't impose disadvantage on your Dexterity (Stealth) checks.
• When you wear medium armor, you can add 3, rather than 2, to your AC if you have a Dexterity of 16 or higher.
• Gain a one in dexterity
• become proficient in firearms and tinker's tools