Ice is halved, and darkness has no effect
Arty knows the fire spell Firebird from the start, and Selan can learn it at the spell shop in Eserikto or Ferim Kingdom (20000G). Arty can also hit the light weakness with Fry or with Zap (65000G) from Durale's spell shop.
Give Maxim the Silver sword from Durale's shop and Guy the Burn sword, found on Flower Mountain, to make normal attacks light- and fire-element respectively
Summons Dark Skull, Hades Skull, and Deadly Sword. Hades Skull acts 2 times in 1 turn. The 2 Skulls are also weak to fire and light, and the IP skill Celestial on Selan's Holy whip hits all enemies at once with light.
The main body's Doomcry is a non-elemental attack on one party member (power 500) with a 40% chance of instant death, and the 2 Skulls also try for instant death with Perish. Party members wearing the Jute helmet (Maxim, Guy) from Tanbel Southeast Tower, the Undead ring from Treasure Sword Shrine, or the Ghost ring, found on Tower of Truth 4F (either ring: all 4), are safe from instant death.
You can be confused by Confuse, Dark Skull's Bite, and Hades Skull's Confubite. Party members wearing the Jute helmet or the Ghostclothes (all 4), found on Tower of Truth 4F, can't be confused.
If confused, cure it with Shriek or the IP skill Revival sleep on Arty's Silver robe. Revive fallen allies with Valor, which Arty knows from the start.