The cantrip light (PHB, p. 255) says that it casts a “bright light”. It also states that:
If you target an object held or worn by a hostile creature, that creature must succeed on a Dexterity saving throw to avoid the spell.
Why would there be specific text directly dealing with casting it on an enemy unless there was some benefit? I was thinking that the spell could either;
- temporarily cause the blinded condition or
- have a similar effect to the Help action and allow an ally to gain advantage on their next attack roll against that enemy.
Either way, I would assume a glowing object would at least give my allies a bonus to see the enemy and make it near-impossible for the enemy to hide while holding or wearing a “bright light.”