Field of Swords gave Jack another ammunition for AOE assaults, which was the preferred assault during a war. The damage didn't seem like much but he would have to see how many swordlights were conjured to make a proper judgment.
Ghost Sword at first glance seemed inferior to Phantom Blade. Phantom Blade had the same feat of bypassing the enemy's defenses and blocks while the actual weapon could still parry the enemy's attacks. However, Ghost Sword dealt higher damage and it was soul-type damage. Additionally, Peniel told Jack that he could still use other skills while Ghost Sword was active. If he used Brave Slash when Ghost Sword was active, the slash would become unblockable.
Jack didn't pay much attention to the Lightning Mine and Magic Clone. Those spells would change once he fused them with Lightning Strike and Body Double. He would have to put fusing those spells on hold. He needed to see his grandfather first.