I think we are not very lucky XDin 80 bags i had found 70 AT/Bard/Sin and 10 of other class

Hey,

I guess this is rather a psychological issue All of the particular stigmata have the same probability (9.09%) to drop from the respective bag.
That means, if you "just want to have any complete stigma set", you would have to open ~11 gold, ~22 blue and ~33 green bags on average.
Since most of the time you want to have "a very specific set of 6 stigmas", you will have to open ~22 gold, ~132 blue and ~297 green bags on average.
If you really want "all stigmas that my class could equip", you would have to open ~44 gold, ~396 blue and ~891 green bags on average (a little less than that).

What I really wanted to say:
There are 11 classes with 187 stigmata in total, which is a lot if you are looking for very specific ones. Experience shows that other people are also getting tons of unwanted stigmas, so collecting and trading is usually the best option

Greetings,
Mud