Welf is a tall adult male who has short, spiky red hair and dark blue eyes. He wears a blue scarf around his neck. His attire consists of a dark blue long-sleeve shirt underneath a black kimono with a brown belt tied around his waist along with tanned white pants and long brown boots. When crafting in the forge, he wears a traditional attire befitting of a blacksmith such as a bandana, t-shirt, apron, and gloves.
Welf Crozzo is a straightforward and honest person. He is generally casual to everyone that he associates with, asking Bell to call him by name and without honorifics the first time they met. He doesn't like to be associated with his family name, preferring to not be a part of the conversation when his name is brought up and even refuses people that come to him seeking magic swords.
Welf holds a deep hatred for magic swords, considering them to be objects that rot the user, as they would always break away and leave the user behind. However, after the battle against the Black Goliath on the 18th Floor, his hatred lessens somewhat, though he still refuses to make magic swords for anyone other than members of his own Familia.
Welf holds a lot of pride in his work. He refuses to let Bell wear armor not forged by his own hands and desires to surpass Hephaestus without using his ability to make magic swords, wishing to prove that he is his own man. While not arrogant, he did let the title of High Smith get to his head for a time, which Tsubaki coldly pointed out when she easily split a shortsword he had made.
Despite making works of good quality, Welf tends to give them poor names, though he doesn't realize it, and gets disappointed when the recipient chooses something else. Both Bell and Mikoto have each fiercely pleaded with him to give their weapons a better name (the Ushiwakamaru and Kotetsu were to be called Minotan and Shimajirou, respectively).
Despite leaving the Hephaestus Familia, he is thankful for everything that Hephaestus has done for him, telling her that he would always remember what she had taught him.
Welf was originally born in Rakia, a nation type Familia ruled by Ares. As a member of the Crozzo Family, he lived as a noble due to the successes his predecessors had in creating magic swords. However, his life changed the day his Skill Crozzo Blood appeared, which enabled him to create magic swords again. Despite his family's joy at the prospect of being able to create more magic swords, Welf despised his skill, causing him to escape Rakia with the help of his former Goddess Phobos.
Will-o-Wisp (ウィル・オ・ウィスプ): Will-o-Wisp is an anti-magic fire that forces an Ignis Fatuus on others trying to use magic. This magic also works against monsters, as Welf was able to cause Hellhounds that were in the process of attacking his party to self destruct.
Crozzo Blood (
Veritas Burn (
Blacksmith (鍛冶): Blacksmith enables Welf to add special abilities to his creations and make better creations overall.
Greatsword (大刀) is a large single-edge sword with a broad blade created and used by Welf Crozzo. It has power exceeding the upper floors. Because it is the weapon he uses himself, he did not name it. As long as it is not a weapon made for others, Welf will not name it.
Portable Smithing Set: Welf carries around a portable hearth and smithing tools, allowing him to be able to maintain and/or repair items whenever and wherever.
Kazuki (煌月): Welf's new fire element longsword shaped unbreakable magic sword. It is the first in the new Shikou (始高) series. As it relies on the wielder's magic, which also influences how strong it can be, it doesn't break like normal magic swords. When Welf uses it, it resonates with his Spirit blood and becomes as strong or even stronger than his normal Crozzo magic swords.
- Welf has some experience at playing the violin as a former noble. However, he describes his skill as "terrible".