Ancestral Whispers

While burning the component incense, you invite or compel the spirit of an ancestor to guide the actions of the creature touched. The creature becomes proficient in a language, skill, tool, armor, or weapon of your choice for the duration of the spell, and its proficiency bonus for the use of that skill or weapon (only) increases to +3 if it is not already higher.

Using a Higher-Level Spell Slot. When cast using a 4th-level spell slot, the duration is 12 hours and the proficiency bonus is +4, increasing to 16 hours and +5 for a 6th-level spell slot, or 24 hours and +6 for an 8th-level spell slot.

Adapted from the D&D 4th Edition ritual of the same name.