Each bardic instrument ends with these sentences:
When you use the instrument to cast a spell that causes targets to become charmed on a failed save, the targets have disadvantage on the saving throw. This effect applies whether you are using the instrument as the source of the spell or as a spell casting focus.
Yet, it appears that only the Doss Lute (which can cast Animal Friendship) has a spell that causes targets to become charmed. None of the other instruments actually have such a spell.
For example:
- Canaith Mandolin: Fly, Invisibility, Levitate, Protection from Evil and Good, Cure Wounds (3rd level), Dispel Magic, Protection from Energy
- Cli Lyre: Fly, Invisibility, Levitate, Protection from Evil and Good, Stone Shape, Wall of Fire, Wind Wall
- Anstruth Harp: Fly, Invisibility, Levitate, Protection from Evil and Good, Control Weather, Cure Wounds (5th level), Wall of Thorns
How can the instrument be the source of a spell causing charm if it doesn't have spells that charm? Can the origin of spells cast by a bard can be shifted to items? Why is the phrase "...when using the instrument as the source of the spell..." used in the instrument descriptions and what does it mean?