It's when attacking with [Frenzy] state, not chance to gain frenzy state.
When dealing physical damage with [Frenzy] state, has a chance to transform into Lord Knight Seyren and gains ATK+1000 for 5 sec.
Hello!
I believe the part increases attack speed (reduces delay after attack by 7%) should be removed since it's not in the KRO description of 'Modification Module (Spell)' https://www.divine-pride.net/database/item/25680/kRO
and Grants Faltal4 Fatal4 to equipment in https://www.divine-pride.net/database/item/25682/kRO