Rank I+ Twilight Children can equip a variety of weapons, which will change to match their Affinity.  Weapons can be found while exploring, through purchasing an adoptable or through Transforming a Rank 0 Twilight Child with a Transformation Item.

The most common weapons are listed below, along with the Class(es) which commonly use them, though some Twilight Children may have rarer weapons which are not listed.

Sword (Magical Knight - Heavy Sword/Mercenary - Light Sword)
Staff (Heavy Magic-User)
Bow (Light Magic-User)
Wand (Light Magic-User)
Glove (Brawler)
Gun (Gunner)

A Twilight Child's Class determines their starting weapon's rarity and their skill handling different types of weapons, though they can learn to use other types of weapons.