How does the family of Smite spells work when a Paladin is mounted on a Paladin's Steed that was summoned by Find Steed spell?
Steed and Paladin share the effects of some spells.
Based on the range of "Self" (Basic rules p. 79, PHB p. 202), and the application of spells to one's Steed (Find Steed, p. 240, PHB) some players assert that when the Paladin casts a Smite spell while mounted on his Steed, both the Paladin and the Steed are under its influence. In the case of a Steed that can fight while bearing the Paladin into battle, they argue that the Steed will also apply the Smite spell's effects to an enemy in a given combat. I don't think that's how it works. A combination of the rules under discussion leads me to three cases.
A Smite spell is cast. (spell descriptions, see Supporting Text). When the Paladin lands a blow while the spell is still active (it lasts for one minute, basically it is a charge up) the effects are applied to whomever the Paladin hit with his attack.
A Smite spell is cast, it charges up both the Paladin and the Steed, and whichever of them lands the first blow would trigger the effect within the next minute.
A Smite spell is cast, it charges up both the Paladin and the Steed, and both the Paladin and Steed trigger the effect upon landing a blow within the next minute.
Range of "Self"
Most spells have ranges expressed in feet. Some spells can target only a creature (including you) that you touch. Other spells, such as the shield spell, affect only you. These spells have a range of self. Spells that create cones or lines of effect that originate from you also have a range of self, indicating that the origin point of the spell’s effect must be you (see “Areas of Effect” later in the this chapter).
The first time you hit with a melee weapon attack during this spell's duration, your weapon rings with thunder that is audible within 300 feet of you, and the attack deals an extra 2d6 thunder damage to the target.
The next time you hit a creature with a weapon attack before this spell ends, the weapon gleams with astral radiance as you strike. The attack deals an extra 2d6 radiant damage to the target ...
The ambiguity arises from the spell description of Find Steed. (PHB 240)
"While mounted on your steed, you can make any spell you cast that targets only you also target your steed."
Case 1 is vanilla application of a Smite regardless of Cases 2 or 3 being True or False.
Case 2 might be true, but I don't think it is RAI. Is it within RAW? I say no, due to the text describing the weapon as glowing with the magical energy and releasing it to the target of the weapon's melee attack.
- IF case 2 is not true, THEN case 3 is not true. But, IF case 2 is true, THEN what?
Case 3 is still NOT true, since the spell text indicates by my reading of it that "one charge up, one release of the smite upon a successful hit."
Case 1 is the only true case. The text in each smite spell shows that the weapon itself is charged up and varies in its appearance based on which spell is charging it up.
Case 2 is not true, but I may have missed something. Since warhorses can fight, and a warhorses hooves are weapons, the argument that it might trigger the damage has some support, but the spell description about glowing weapons suggests to me otherwise.
Case 3 is not true, since that provides TWO triggers for one cast of the spell. IF that were true, you'd also be able to argue that a two weapon wielding Paladin would get two smites from one spell.
A Good Answer
A good answer will either confirm I am right, or show what I've missed or misunderstood in the rules for Cases 2 and 3.
Question restated: How does a Smite spell work on a Paladin mounted on his Steed from Find Steed spell?
(Note. IF the steed cannot fight while bearing the Paladin in battle, THEN the entire point is moot).