Facing Jad Head-on II is a grandmaster combat achievement which requires the player to kill TzKal-Zuk without using any ranged and magic weapons prior to fighting him.
Justiciar armour and Dinh's bulwark are absolutely mandatory for the massive defence bonuses and passive effect provided by justiciar. A Saradomin godsword is recommended to restore health and prayer points. Even then, try to get as few enemies as possible attacking to avoid the chances of getting combo'd out.
The player is still allowed to cast spells as long as they don't equip a wand or staff; as melee armour provides negative magic bonuses, they will need to be taken off in order for the spells to hit.