Is a Blade Pact Warlock proficient when wielding their pact weapon in an improvised fashion?

Question

The Pact of the Blade Warlock is proficient with their pact weapon while they wield it. Suppose that a Blade Pact warlock is wielding a longsword as their pact weapon (either because they created a longsword, or because their bound pact weapon happened to be a longsword). They decide that they would like to deal bludgeoning damage this turn, so rather than switching to a different weapon they hold the sword by the blade and strike using the crossguard or pommel.

Do they add their proficiency bonus to their attack roll, even if they are not otherwise proficient with improvised weapons?

Answer 1

Proficiency with a weapon does not grant proficiency in improvised attacks using that weapon

This fact is covered in the following:

• When throwing a melee weapon without the thrown property is the proficiency bonus still added to the attack?

To quote the highest-scoring answer:

With this information, you effectively have two choices:

1. Have your DM treat the original weapon as a second, different weapon that has the Thrown feature. Example: treating a Halfling's War Hammer (no Thrown) as a Goliath's Light Hammer (with Thrown).

2. Make your attack as using an Improvised Weapon, dealing 1d4 damage and using the default thrown option of 20/60 range, and only adding proficiency if provided by another feature (as from Kensei or Tavern Brawler).

Assuming the Warlock does not have a feature such as the Tavern Brawler feat granting them proficiency with improvised attacks, using their Pact weapon in order to make an improvised attack would result in their attack not using their proficiency bonus unless the GM ruled that the improvised form of their weapon is close enough to some weapon that they do have proficiency in that it the attack can effectively be considered to be using that weapon.

In this case, a GM could rule that using a Longsword to deal bludgeoning damage is perhaps similar enough to a Club or some other simple weapon that Warlock's already have proficiency with. If the GM did decide this, then the Warlock would add their proficiency bonus to the attack roll; however, if the GM does not consider the Longsword being similar enough to another weapon, then the Warlock does not add their proficiency bonus to the attack roll.

Answer 2

I'd go with the following: Because what you describe is basically Mordhau. It was a real thing in medieval sword combat... but it was an improvised use of the weapon. But rather spending a feat just to do a Mordhau, I'd rather suggest to spend a downtime and a few gp to simply train that attack with a teacher for improvised weapons.

For more information about Mordhau... here's its disappointingly short wikipedia article:

In the German school of swordsmanship, Mordhau, alternatively Mordstreich or Mordschlag (Ger., lit., "murder-stroke" or "murder-strike" or "murder-blow"), is a half-sword technique of holding the sword inverted, with both hands gripping the blade, and hitting the opponent with the pommel or crossguard. This technique allows the swordsman to essentially use the sword as a mace or hammer. The Mordhau is mainly used in armoured combat, although it can be used to surprise an opponent in close quarters.

and here's a video https://www.youtube.com/watch?v=2e0xr-aZJos

RAW it's totally fine to use a weapon as improvised.

Improvised Weapons

Sometimes characters don't have their weapons and have to attack with whatever is close at hand. An improvised weapon includes any object you can wield in one or two hands, such as broken glass, a table leg, a frying pan, a wagon wheel, or a dead goblin.

In many cases, an improvised weapon is similar to an actual weapon and can be treated as such. For example, a table leg is akin to a club. At the DM's option, a character proficient with a weapon can use a similar object as if it were that weapon and use his or her proficiency bonus.

An object that bears no resemblance to a weapon deals 1d4 damage (the DM assigns a damage type appropriate to the object). If a character uses a ranged weapon to make a melee attack, or throws a melee weapon that does not have the thrown property, it also deals 1d4 damage. An improvised thrown weapon has a normal range of 20 feet and a long range of 60 feet.

So, a longsword wielded with Mordhau could resemble a Warhammer or a Greatclub. So if you're proficient with Warhammers or Greatclubs and Longswords you theoretically could use your Longsword with Mordhau.

Because an improvised weapon can be

any object you can wield in one or two hands

Check!

And...

In many cases, an improvised weapon is similar to an actual weapon and can be treated as such

Check!

So it's pretty much up to your DM whether he or she thinks a Mordhau Longsword is a Warhammer, a great club or a two handed weapon that deals 1d4 bludgeoning damage. TBH every character that is proficient with simple and martial weapons should be able to perform a Mordhau or a similar strike. I mean it's a very minor tweak and implements a very interesting sword technique.

For the Blade Warlock it's a little bit different anyways, because you are always proficient with your pact weapon. To switch between slashing and bludgeoning for a damage decrease is a pretty okay effect that shouldn't be take too much effort for your character. Sure it's a bit of a stretch of improvised weapons to use actual weapons as improvised weapons... but I really don't see any occasion that it could break the game. Comment me, if I miss smth.

Answer 3

DM's choice

Firstly:

they hold the sword by the blade

Your character should never do this. Blades are meant for cutting, not holding. Holding one in your hands is a bad idea - how bad depends on how mean your DM is.

You can make a pommel strike as part of normal sword fighting, it just isn't a rule included in 5th edition D&D (earlier editions did have weapons with multiple damage types).

As such, what you are asking isn't covered by the rules. I would personally rule that you get your proficiency bonus to attack since pommel strikes are a part of actual swordfighting, but for damage I'd only allow the 1d4 for an improvised weapon since you won't get as much power from the attack.