I'm not a very big melee fan to be honest, so I've never really understood the hype behind berzerker axes. I find decapitators (I actually have 2 4 socket decaps) on a regular basis. Is it because it's a six socket one hand weapon?
ethereal berzerker axe is popular mainly because of the new 1.10 BOTD runeword.
ethereal - since BOTD has zod in it, the weapon becomes indestructible, thus allowing for the use of ethereal weapons, which get 50% extra base damage for being ethereal.
berzerker axe - it's the best 1-handed melee weapon that can get 6 sockets. it's a little slower  than the war spike [-10] which is the 2nd best eth 1-handed weapon to have (also can have 6 sockets) but has more damage.
get a good % enhanced damage on the BOTD runeword if you're lucky, and you'll be doing about the same damage as the previous (now extinct) ith berzerker axe.
my pally loves his eth BOTD zerk axe. I just wish it had +skills on it though.
6 290's in my inventory, and 6 skill charms (offense and combat). I do 11k max charge currently. lvl 94 and I still have about 20+ skill points to throw in synergies to increase the damage some more. gonna increase damage for zeal, charge and vengeance.