How can a PC cast Elemental Weapon using a spell slot higher than 5th level?

Question

In the PHB, the Elemental Weapon spell has a stronger effect when cast using a spell slot of 5th level or higher, with a 7th-level slot described as providing the strongest effect. However, in the PHB the only class that has the spell on its spell list is the Paladin, which only gets up to 5th-level spell slots according to its advancement table.

What methods (if any) are available for a PC to be able to cast Elemental Weapon using a spell slot higher than 5th level?

Answer 1

There are several class options with access.

Although Paladins can cast it at 5th level maximum, the fact that they can't cast it at 6th level is irrelevant for this answer, since the 5th and 6th level versions of the spell have identical benefits. Since 7th, 8th, and 9th level castings all have the same effect, let's assume casting it at 7th level is the minimum relevant solution.

There are non-Paladin class or subclass options with access to elemental weapon and the ability to cast the 7th level version of the spell, including the following:

• A Cleric of the Forge domain, whose expanded spell list allows them to prepare elemental weapon at 5th level and who gains 7th level slots at 13th level.
• A Bard, who can learn elemental weapon using Magical Secrets at 10th level (or at 6th level if they are of the College of Lore) and who gains 7th level slots at 13th level.
• A Paladin of 9th level who is multiclassed as a 9th level "full" caster class (Bard, Cleric, Druid, Sorcerer, or Wizard). This 18th level multiclass character can learn 3rd level Paladin spells and has 7th level spell slots.
• Any spellcaster who can learn the wish spell and who has a 9th level slot with which to cast it (such as a 17th level Sorcerer or Wizard) could use it to duplicate the effect of a 7th level elemental weapon (see this related Q/A for an explanation).
• Future class or subclass options not available at the time of this posting or current options not available in the core rules. Many spells and other features are written with future-proofing in mind (such as spells that conjure creatures of a certain CR at higher spell levels when no such creatures are published yet).

Magic items might make it happen.

If a character is capable of casting a scroll of 7th level elemental weapon or if some other magic item can be used to create the effect of a 7th level elemental weapon spell, the spell's description covers the higher level effect.

Answer 2

The common way for doing so in a single class is by being a Bard. When you hit 10th level as a Bard (or 6th as a Lore Bard), you get access to the feature "Magical Secrets", which lets you add any spell to your spell-list, and Bards can cast 9th level spells.

However, Elemental Weapon is only a 3rd level spell. Paladins get access to these at their 9th paladin level, so another way of doing it is by being a Multiclass character. (This is an optional rule, so check with your DM.)

If you have 9 levels of Paladin and 11 levels of full-caster like Cleric, you'll be a 15th level spellcaster, which gives you access to 8th level spell slots. You can use these to cast Elemental Weapon as well.

There also exist a few options for adding specific spells to your class list, such as a Warlock's Patron, a Druid's Land Circle, or a Cleric's Domain, but I do not know of any that let you add this specific spell to your spell list.