Would allowing Shillelagh to transform your staff into another weapon be unbalanced?

Question

I am planning a (not explicitly optimised) Ranger/Monk character, that uses Druidic Warrior to cast Shillelagh:

Druidic Warrior

You learn two cantrips of your choice from the druid spell list. They count as ranger spells for you, and Wisdom is your spellcasting ability for them.

The spell in question:

The wood of a club or quarterstaff you are holding is imbued with nature's power. For the duration, you can use your spellcasting ability instead of Strength for the attack and damage rolls of melee attacks using that weapon, and the weapon's damage die becomes a d8. The weapon also becomes magical, if it isn't already. The spell ends if you cast it again or if you let go of the weapon.

However would it be unbalanced to ask a DM to allow it to transform into a sword as part of the spell (while retaining all other properties including the 1d8 damage)? The only thing I can think of us the damage type changes from bludgeoning the slashing.

Part of motivation is flavour: magical weapon cool; magical transforming weapon, way cooler.

The other part is that if I picked Kensei as my monk subclass, I could pick Longsword as my Kensei weapon, and have my Shillelagh count as that.

Answer 1

Is converting bludgeoning to slashing damage balanced? Yes, according to the Great Monster Spreadsheet!

Damage type generally only matters in the context of vulnerabilities, resistances, and immunities. For instance, force damage is much more powerful than poison damage, since so many monsters have resistance/immunity to poison, but almost none have any kind of advantage against force. If two damage types generally have the same amount of vulnerabilities, resistances, and immunities, then they're pretty much interchangeable except in special circumstances.

Reddit user u/RufflesDmAccount put together this spreadsheet of all the monsters in D&D 5e, including their damage sensitivities. Sifting through the data with some regular expressions, we find the following counts:

	Vulnerability	Resistance	Immunity
Slashing	0	8	2
Bludgeoning	6	8	0

So bludgeoning is a slightly more powerful damage type than slashing, having a few more vulnerabilities and no specific immunities, but it's very slight. You won't lose any combat effectiveness unless you're fighting a horde of skeletons, and this is definitely a balanced change.

Answer 2

You can have it look like a sword, but it still does Bludgeoning damage.

According to Tasha's Cauldron of Everything on Personalizing Spells, it's allowable to change the aesthetics of a spell, as long as the mechanics (including damage types) remain the same, and the spell isn't being hidden as a different spell. For instance, one of the examples given is a wizard with a storm magic theme casting a Fireball that looks like a ball-shaped mass of red lightning (but still does Fire damage, not Lightning damage).

For example, the fireball of a wizard with a fondness for storms might erupt to look like burning clouds or a burst of red lightning (without affecting the spell’s damage type)

So, if a Ranger, when casting the Shillelagh spell makes their club or staff look like a sword, that's fine, as long as its mechanics remain the same, since it's not mimicking the effects of other spells. So, in this example, your wooden sword would still do 1d8 Bludgeoning damage. Additionally, it would still count as a club or staff for the purpose of your Kensei Weapon if you choose Longsword for that feature, since that would be another piece of mechanics that remain unchanged.

Answer 3

It depends on the build of your character and DM homebrew

Shillelagh was specifically made for spellcasters where their spellcasting ability score means more, and before Tasha's came out, Rangers didn't get any cantrips. So already this combination is more powerful for Rangers.

Potential unbalanced of a Magical Transforming weapon with a cantrip

If your DM allows you to transform the damage type of your weapon, you can potentially target enemy weaknesses easier while only using up a bonus action and not a full action like Warlock's Pact of the Blade.
There aren't many monsters with vulnerabilities to bludgeoning, piercing or slashing, but it might depend on the homebrew your DM composes.

Damage Output

By using Shillelagh you can focus more on increasing wisdom. Your Ranger spells become more reliable, you deal more damage and increasing your WIS over DEX doesn't affect your Monk Unarmored Defense AC.
This also increases the chance of incredible powerful abilities like Stunning Strike working.

The only detriment I can see is the damaged dealed by your bonus action unarmed strikes & Flurry of Blows. With a general lower DEX score, you are less likely to hit and deal slightly less damage, but you could easily make this up by the damage output of Hunter's Mark on your main attacks & use your bonus action for other monk Ki abilities.

However saying all this, there is no reason to why you cannot choose a quarterstaff as your Kensei weapon anyway.

Talk to your DM

If you are worried about balance, simply ask your DM if you can do this. I personally would allow it as it won't change much from using a quarterstaff anyway.