18 Jan Blade Ward 5e D&D Guide 
Here we’re looking at the cantrip blade ward, which is on the Bard, Sorcerer, Warlock, and Wizard spell lists. While it is not a stellar cantrip on the level of the reliable damage of firebolt or the utility of prestidigitation, it is not a truly bad option.
The rules for blade ward, found on page 218 of the Player’s Handbook, are as follows:
Blade Ward 5e
Casting Time: 1 action
Components: V, S
Duration: 1 round
You extend your hand and trace a sigil of warding in the air. Until the end of your next turn, you have resistance against bludgeoning, piercing, and slashing damage dealt by weapon attacks.
Looking very simply at the rules, this cantrip is very basic – you give up your action to become resistant to the three physical damage types. There are some nuances here, both good and bad, which deserve further analysis.
Why Blade Ward is Bad?
The first and lesser limitation of the spell comes from the preciseness of its wording – note that the resistance gained only functions against weapon attacks that deal those damage types. This means that if you take bludgeoning, piercing, or slashing damage from any source other than weapon attacks, this cantrip does nothing against it.
Probably the most common example of this is falling damage, which deals 1d6 bludgeoning damage for every 10 feet you fall, to a maximum of 20d6 damage. Spellcasters wanting to protect against this should instead take the feather fall spell, which ignores all falling damage.
Other sources of non-weapon physical damage are far rarer and generally come from environmental effects such as falling boulders or from spells, like catapult.
The second limitation of the spell is that it requires a full action to cast. This means that you cannot use your action to Dash, Disengage, cast a spell, make an attack, etc. If we dive briefly into what is known as ‘action economy,’ we can see why this is a bad idea.
An average D&D party of four members (let’s take the classic combination of Fighter, Rogue, Wizard, and Cleric) is going up against an equal number of enemies, such as bandits. In a full round of combat, each creature gets a turn, consisting of movement, actions, bonus actions, and reactions. Because there are even numbers, the action economy is said to be balanced.
However, if the Wizard, in this case, uses their action to cast blade ward, they are not actually spending their action doing anything that will help their party win this fight. Sure, the Wizard will take less damage if any of the bandits attack them, but they will still take half damage.
If the bandits simply attack the rest of the party, and the party (excluding the wizard, because they are casting blade ward) attack the bandits, then it becomes 3 attacks from the party’s actions against the 4 from the bandit’s actions. Assuming that the party is not exceptionally more powerful or well-armed than the bandits, simple math dictates that the party will most likely lose this engagement.
From this, it should be quite clear that using one’s action purely defensively is generally not the best course of action to take. However, there are some exceptions, which I will go into below.
Why Blade Ward is Good?
On the surface, blade ward is only situationally good – if you as a spellcaster have been caught in a bad position by a hostile creature, then it might be a good idea to cast this spell to protect yourself for this turn, with the intent that you can escape or rely on your party members to back you up. As mentioned in my action economy discussion above, this isn’t great, but it might save your life against something particularly nasty and isn’t so bad if it is for a single turn of a fight.
However, spending one of your very few cantrip options on something designed to mitigate a mistake that might situationally occur is not exactly what you can justify as good. Instead, the usefulness of blade ward becomes apparent when it is used in conjunction with certain subclasses that can mitigate this loss in action economy.
The first of these comes in the form of the Eldritch Knight Fighter subclass. Eldritch Knight’s can learn and cast a limited number of spells from the Wizard spell list, but only from the evocation or abjuration schools of magic. Fortunately, blade ward is an abjuration spell, so this is fine.
The real synergy occurs once we look at the Eldritch Knight’s 7th-level feature, War Magic. This allows the Eldritch Knight to make an attack with a bonus action if they used their action to cast a cantrip. In a particularly tough fight, it might be the best idea for such an Eldritch Knight to focus on fortifying themselves rather than doing the most damage, in which case blade ward becomes quite a good choice as it allows the Eldritch Knight to take reduced damage and still attack at least once a round.
The second comes from the Bladesinger Wizard subclass. At 6th level, a Bladesinger can attack twice thanks to their Extra Attack feature and can substitute one of these attacks to cast a cantrip. This is similar to the Eldritch Knight above, allowing the Bladesinger to both attack and defend simultaneously, but is slightly better as it uses only an action on a turn, rather than both an action and a bonus action.
Final Thoughts: Is Blade Ward Good or Bad?
On its own and when used consistently, blade ward is quite a poor cantrip choice. However, when used situationally and synergistically and in a way that does not affect the action economy, blade ward definitely has some uses, so it cannot be written off as a completely bad option.