Something about fusion bolt makes it special but I can't remember what:it's somewhere here on the forums... But the mastery affects for sure are not additive.
Hi, I saw your buying thread about buying a hat with mastery damage. Just letting you know that mastery damage is NOT additive, it's multiplicative as in level 20 (which gives 10%) will just add 10% do your respective mastery bonus making it 11% NOT 20%. If it was the latter, everybody would be chasing after it, but it's not unfortunately :c.
Your mabinogi details.
Vindictus character information (mabinogi heroes).