Rune Saber is a ground magical Bravery to HP attack for Warrior of Light, obtained after obtaining Ascension. It requires 40 CP to equip (20 when mastered), 300 AP to master, has Melee Mid priority, and deal up to 12 damage, and generates up to 160 EX. The midair version is identical, but is obtained after learning Crossover.
Both versions of Rune Saber return as a Bravery to HP attack for Warrior of Light, now requiring 30 CP to equip (15 when mastered) and 130 AP to master both versions. They now only deal 10 damage and generate no EX Force.
Runes are the letters in a set of related alphabets known as runic alphabets, which were used to write various Germanic languages before the adoption of the Latin alphabet and for specialized purposes thereafter. Historic anthropology regarding the Germanic and Norse peoples that used runes also note that the language was also highly used in magical practices related to these cultures, whether it be in divination, enchantment, and incantation.