Well, many kills besides GF + AH were made with auto aiming skills (HB,Homing Nova, MM) or Abyss that is stationary, 'long' lasting and has incredibly high dps.
Playing with a skill that you actually have to aim Samael with, will make dodging all his spells and the worms projectiles much more difficult while doing consistent damage.
So imo that item will boost elemental damage to it's limits but elemental itself is not a viable Sam Killer skill.