Alphen is the lead character of Tales of Arise, and much of his power comes from the Flaming Sword that he’s able to wield.
Alphen’s unique ability, he’s able to wield the Flaming Sword quite early on into Tales of Arise, but it’s not something you just equip. Instead, it’s something that you use sparingly, as while it does great damage to the enemies it hits, it also drains Alphen’s HP when used.
To use the Flaming Sword, when playing as Alphen in battle, you need to perform a ground based Arte then keep the button held down. After performing the Arte, Alphen will then pull out the Flaming Sword and perform a devastating fire-based attack.
There are some things you should be aware of, however. One is that if you’re hit by an enemy attack before Alphen performs the Flaming Sword skill, it may be interrupted. Also, there are various Flaming Sword skills available – head into the Artes menu and look at each Arte to see what Flaming Sword skill is associated with it.
As you get further into Tales of Arise, you can further bolster Alphen’s Flaming Sword skill, making it more powerful at the expense of it draining more HP, and more. Make sure to use it effectively, as it can really turn the tide of battle. Particularly so when facing off against enemies weak to fire.