It wasnt intended for solo DRG as no job was ever intended to solo even BST, according to SE developers. Gungnir's aftermath was created under the pretense of DRG's original role as a low enmity damage dealer. DRG's original role was to deal large amounts of damage split between the master and the pet(so hate is split instead of one large hit for damage, it would be one decent hit followed by a weak hit from the wyvern, to split enmity), high jump to shed hate and super jump to erase hate. I suppose they figured the shock spikes would also reinforce DRG's enmity gaining buffer so that if/when they DID pull hate the shockspikes stun would negatively impact the mob...though the proc rate is floored at 5% on level 0 Rabbits or Arch Dynamis Lord, doesn't matter.

I've suggested they either make the stun vastly more potent or accurate or make it Enthunder animation but the additional damage is based on wyvern's current HP(like Excalibur's additional effect that occasionally adds 25% of your current HP to your hit). So if the wyvern has 1000 HP, then occasionally your Gungir's melee hit will add a 250 damage Enthunder to your hit.