You quickly change from a defensive shield stance and offensive sword stance. This allows you to lock down for a impetrative defense and all out attacks making you a fearsome presence on the battle field.  

Stance Change

At third level you gain the ability to switch between a defensive and attack stance as a bonus action. You also gain different skills depending on what stance you are currently in.

Sword Stance

While in attack stance the bonuses from unarmored defense are transferred to your unarmed strikes, and your ac drops to 10.

Shield Stance

While in Shield Stance you add you proficiency bonus to your ac, and you speed is cut in half

Retaliate

Starting at level 6 when you are hit while in shield stance you can use a reaction to force the attacker to move back 10 feet.

Hailstorm of Blows

At level 6 while in Sword Stance you can use 3 ki points as a bonus action to do 4 unarmed strikes.

Shield Bash

At level 11 your defense becomes so solid you can use it for offence. If you move more that 15 feet in one direction you can throw your entire weight into a foe. The target takes 2d6+ your unarmed strike bonus and must make a strength save of your monk level plus your proficiency bonus.

Disarming Strike

At level 11 you can use a ki point to make a disarming strike. You hit your the target in the hand and they must make a dex save of your monk level plus your proficiency bonus. On a failed save they drop their weapon

Flow State

At level 17 you gain mastery of your Shield stances. You can take brace as a bonus action.

Hardened Sword

After all of your training your body has become hardened and more defensives even in a valuable stance. While in Sword Stance add you proficiency bonus to your ac.