I must say that the low-cooldown skills of Sven are kinda strong!! His zerk can summon the wyvern in 2 turns and his warlord counterpart can summon his in 3 turns. based on my guildmate's report, sven zerk is really suicidal, the very trait of a zerker so healers with persistent heal or with a high solo heal is a must and his dragon is really strong! On the other hand, the warlord is a very good ATK buffer and a solid build DPS! I really like sven but I couldnt wonder how Vincent and Leah can match up with him now
I believe Zerk has a little margin over the Warlord but he needs constant support not to kill himself. He is also nice in trigger teams!
Zerk for SDD Team; Warlord for Team with solid DPS for shared ATK Buff.