It really depends on your style of playing, so it's your choice. In researching various sources for character builds of my own I found this piece of advice:
Wait before allocating points to your Weapon Mastery and see which powerful weapons your Barbarian finds. When you find a really powerful weapon you like then this may be the Weapon Mastery you will want to allocate points to.
Because the Barbarian can wield a one-handed weapon in each hand (duel-wield) I've thought of putting 10 points in Sword Mastery and 10 points in Axe Mastery and then giving him a powerful sword and axe. This would also allow you to equip combinations like the Berserker's Arsenal Set with a powerful sword, just for one example. Of course, putting 20 points in one Weapon Mastery would make the Barbarian even more powerful with that type of weapon and you can still equip two of the same type of weapon (two powerful axes or two swords). There are many possibilities.
Also keep in mind that you don't have to have points in a particular Weapon Mastery to use a weapon, but it wouldn't be as powerful, so why would you put a lot of points in one Weapon Mastery only to use a different weapon.
I hope this helps. There are many game sites that offer documentation on character builds, including Arreat Summit. Bing (or google) D2 character builds and see what you get.
When all else fails... remember, we now have Respecialization (respec)! ;P
To each his own... I own one of each! ;)