I went to investigate since it seems, like to be written weirdly, but according to the author:
"It was only ever supposed to be one free Skill Trick, but then I was told that wasn't clear... I tried to fix it, but apparently it still isn't clear. Alas.
Add that to my running list of "If I had it to do all over again" From Danielle Lauzon, Trinity Mechanic leads.
I also thought it was a skill trick for every dots above 3, but it is supposed to be only one.
In short the rule is:
for every skills with 3 or more dots, you get a specialty.
You start with one skill trick for free.