Conan

For this achievement you have to master all dual wield attacks.
First you have to buy an attack and then you have to use that attack to master it. Usually you have to use it between 10 - 20 times to master.
Now here is the tricky part of Conan.
There aren't enough points to buy all attacks and there aren't enough enemies around to master them all. So choose your tree for the weapons skills. Don't go for dual wield AND one handed AND two handed weapons but choose one and specialise. Of course you can put some points in the other weapon masteries but not too many. It took me 3 separate runs to get the three weapon masteries achievements.

NOTE: Do NOT activate the cheat "Master All Moves" if you want this achievement.

The above solution captures most of it. But here are the last details. I was able to get dual wield and one handed in a single playthrough. Of course I specialized in one tree first and then moved to the next.

The key is that for it to count the last part of the combo must make contact (i.e. not be blocked) So for many of them you can start from farther away and press XXX, then on that last one you need to make contact. This minimizes the chance your attack will kill the enemy and it will still give you credit, so you can use it multiple times on the same enemy. Some attacks, like parries, are fatal on contact though.

You also get bonus points for mastering combos, rescuing maidens, and opening treasure chests

When you press the back button and go to the picture of two crossed swords, it will give a list of combos that you can do with the dual wield. Concentrate on one "discipline" at a time because you will not be able to get all three on one playthrough.

Most of the combos are pretty straightforward. If you perform the combo successfully, it will tell you onscreen what % complete you are with that particular combo. You can also check how close you are using the same menu I mentioned earlier. As someone else metioned, only the last attack of the combo needs to hit, but some attacks will stack (IE you get credit for both a YYY and a YYYY combo if the last two attacks hit)

You can get two disciplines in a single playthrough without much difficulty. If you choose to do this, I strongly recommend getting the parry kill attacks for two different disciplines done first. In the later levels there are very few enemies that you can get parry kills on.