How do you get David's Harp with the console?

effect create_artifact_pedestal_david_harp_effect = { OWNER = root } — runs the scripted effect that makes it, for the character you play (debug mode).

What if the owner can't benefit from David's Harp?

They get Court grandeur baseline +6, Monthly Prestige +4%, Attraction Opinion +10 instead.

Court artifact · Pedestal Item

David's Harp

IllustriousUniqueHoly relic

David's Harp is an illustrious pedestal item artifact in Crusader Kings III: Court grandeur baseline +6, Monthly Prestige +4%, Knight Effectiveness +20%, Number of Knights +2, Monthly Piety per Knight +3%, Max Courting Schemes +1 and 1 more. Quality 100 and wealth 100; maximum durability 150, and it does not wear out. Patch 1.20.0.3, from game/common/scripted_effects/01_exp1_historical_artifacts_creation_effect.txt.

Quick answers (3)

What does David's Harp do in CK3?: Court grandeur baseline +6, Monthly Prestige +4%, Knight Effectiveness +20%, Number of Knights +2, Monthly Piety per Knight +3%, Max Courting Schemes +1, Attraction Opinion +20 (patch 1.20.0.3).
How do you get David's Harp with the console?: effect create_artifact_pedestal_david_harp_effect = { OWNER = root } — runs the scripted effect that makes it, for the character you play (debug mode).
What if the owner can't benefit from David's Harp?: They get Court grandeur baseline +6, Monthly Prestige +4%, Attraction Opinion +10 instead.

This is a wooden, ancient harp. It is rumored to be King David's harp, and to have mystical healing properties.

Effects

For an owner who can't benefit from it

The template gives these instead of the effects above when its “can benefit” check fails:

Who can benefit (can_benefit) (5 lines of game script)

OR = {
	jewish_artifact_access_trigger = yes
	christian_artifact_access_trigger = yes
	islamic_artifact_access_trigger = yes
}

As written in game/common/artifacts/templates (david_harp_template).

Counts as a holy relic for (is_holy_relic) (14 lines of game script)

OR = {
	religion = religion:judaism_religion
	religion = religion:christianity_religion
	religion = religion:islam_religion
	main_rite = {
		rite_has_parameter = jewish_syncretic_actor
	}
	main_rite = {
		rite_has_parameter = christian_syncretic_actor
	}
	main_rite = {
		rite_has_parameter = islamic_syncretic_actor
	}
}

As written in game/common/artifacts/templates (david_harp_template).

History and who has it

Made before recorded history in Jerusalem.

How it is made

The game creates it with the scripted effect create_artifact_pedestal_david_harp_effect. In the console (how to open it), this gives it to the character you play:

effect create_artifact_pedestal_david_harp_effect = { OWNER = root }

Built from the effect's file; not run in the game by us.

Source: game/common/scripted_effects/01_exp1_historical_artifacts_creation_effect.txt, common/modifiers (david_harp_modifier), common/artifacts/templates (david_harp_template) and the English localisation, Crusader Kings III 1.20.0.3.