Imo dreadspikes could be a little cheaper(because of DRK lack of mp recover options) outside that it's fine tho i'd like a longer duration.

W/ out haste you can keep it up 50% of the time
w/ haste(15%) you can keep it up 60% of the time

Now to the point in abyssea /MNK with counter stance you can hit 60-70% counter rate meaning u take near 60%-70% less DMG and dread spike will cover 2187 hp w/ counter it covers 6k Worth of melee DMG w/ -dmg% gear it'll cover 7500 in DMG and in 60 secs there not many mobs that deal that much melee dmg in 60 secs which means DRK with /MNK in abyssea is invincible "to melee DMG" 50-60% of the time (66% with march)

Now to the point dread spikes is v/strong when used in the correct situation but it's not melee DMG that kills DRK it's WS/Ja/Magic that kills us and honestly Dread spikes II isn't gonna fix that