Guild Wars 2

Lets see how many skills you can use in a fight…

Ele 4 attunements
20 weapon skills (5+5+5+5) + 5basic
Tot: 25

Engi kit
From 20 to 30 (something like that… it is hard to explane it)
Tot: 20/30

Others classes 2 weapon set + special class skills
10 skills (5+5) + 5basic + 1/3 special
Tot: 16/18

Why???
Can some one explain it to me?

In my opinion 3° weapon set should be fair.

Because thats how it works, and no one complains. Its fine

Ok… but my ele can cast 25 skills and my guardian only 18.
Nobody complain it but it is still unfair.

The classes are designed with that in mind. Elementalist skills on the whole tend to be less powerful or have significantly longer cooldowns than equivalent weapon skills on other classes, and the cooldown on an attunement after switching out of it is 150% the cooldown on switching between weapon sets.

It’s not an imbalance, because it’s balanced by other things.