That's sigils, not Sigil.

It's time for another Chronicles of Spellborn developer journal! This one explains everything you might have wanted to know about Sigils.

A well known fact about Spellborn is the non-stat armor and weapons. To make sure players can still customize, tweak and tune their fighting characteristics whichever way they like, we have a wide variety of Sigils. These can be collected from different sources in game like quests and loot.
Sigils are items with ‘magical effects’ which can be used when they are equipped one way or another. There are three types of sigils: Skill-, Jewelry- and Weapon sigils. I will handle the Jewelry- and Weapon sigils first as ‘item sigils’ and conclude with the Skill sigils.

Read it at the Spellborn website.