Kill 20 enemies with a Long Weapon.

In order to get this achievement you must kill 20 enemies with a long weapon.

1. Long weapons can be unlocked at any shop in Paris. Although you do start off with a weak one so that should do you.
2. The best way to do this is find a large group of guards and attack and kill them all with your long weapon. Then this will get you about 5, just walk down the street and kill every guard you see.
3. This will eventually get you the achievement.

The long weapon you start off with isn't the best and I highly recommend you buy a better one if you want to get this achievement easily.
It doesn't matter which sort of guards they are either, both types will do.

If you need any help feel free to PM me.