Bonus (Defence+Attack)
Bonus (Style+Size)
Add / Remove a Glyph
Glyph Fusion
Interface
Open your companion window (right click on your name -> Companion).
After select a pet and click on Glyphs.
At first you have only one slot, you have to level your pet for more (6max).

You can´t add more than 4 attack or defence Glyphs.
4 slots are for defence / attack + 2 slots for Style / Size

How to get them?
Attack/Defence 1%-8% = new pet runes (open them, random chance), BoW reward boxes
Size 11-20 + Style = new pet runes (open them, random chance)
More Style, Size 22 = CashShop
It's possible to trade Glyphs with other players if you remove them from your companion.