AC4: Disarm and kill 3 agile guards with their own weapon

If you are not aware of what's going on, the "disarm and kill 3 agile guards with their own weapon" challenge can be one of the most frustrating Abstergo Challenges in Assassin's Creed 4: Black Flag.

Agile guards are the guards that have no hats, wear powdered wigs and fight with a dagger.  They are most commonly found on rooftops acting as lookouts for the guards with bayonetted muskets.  Disarming them is simple: go into unarmed mode (hand icon), wait for the guard to attack, counter the attack and hit the Disarm button.  On the Xbox One and Xbox 360 this involves countering with the [B] button and disarming with the [A] button.  The problem most people will have at this point is that the weapon will drop to the ground and you won't be able to pick it up, making it impossible to kill the guard with his own weapon.

The fact that the weapon drops to the ground is your clue.  This happens with any weapon that you are already armed with.  If it happens to you, then it means you are currently carrying a throwing knife.

I can hear many of you groaning already.

So here's the simple answer: discard your throwing knife before trying to battle an agile guard.  You can do this by selecting the throwing knife (left three times on the D-pad for Xbox and PlayStation), and then throwing it at somebody ([Y] button on Xbox) or by throwing it away -- zoom in with the left trigger on Xbox/PlayStation and throw it with the right trigger.

Now that you are not holding a throwing knife, switch to being unarmed, antagonize an agile guard, wait for his attack, counter ([B] button), disarm ([A] button) and then throw his own knife at his throat ([Y] button).  When you successfully disarm the guard while unarmed, the knife is automatically selected as your projectile weapon for the remainder of the fight.

There you go!  Now go take revenge on those English and Spanish brigands!


NOTE FOR PC USERS:

It seems there is a problem selecting the throwing knife on the PC that hasn't been patched yet.  Fortunately, there is an easy fix for the problem.  You can view it here.