How does the weapon attack as a bonus action mentioned in the Eldritch Knight's War Magic feature work?

Question

How does the weapon attack as a bonus action mentioned in the Eldritch Knight's War Magic feature work?

1. As an example, if I have a longsword in my main hand and cast a cantrip (or higher-level spell, with Improved War Magic), can the attack I take as part of War Magic be the longsword in my main hand even though attacking with it would normally require using the Attack action?

2. The same scenario as the above example, except I have a short/longbow. Can I fire the bow as my weapon attack from War Magic?

3. The same scenario as the above example, except using either the versatile feature of the longsword to then swing it with two hands or using a greatsword. Can I swing a two-handed weapon or the longsword as a two-handed weapon as the weapon attack from War Magic?

I'm interested in answers approaching this from either a RAW or RAI (rules intent) perspective.

Answer 1

War Magic lets you cast and attack on the same turn.

Question 1: Yes, this lets you attack without the "Attack" action.

The War Magic feature lets you make one weapon attack as a bonus action. This is conditional on having used your action to cast a cantrip, and having a bonus action available.

Logically this implies that the cantrip should occur first, although the 2017 Sage Advice Compendium (which is considered RAI and not RAW) suggests that either order is okay if the DM allows it.

Note that this weapon attack is not "the Attack action", so your Extra Attack features don't apply.

Questions 2-3: Yes, you can use a two-handed weapon for this attack.

You can use a bow, two-handed weapon, or versatile weapon with two hands for this weapon attack. Neither War Magic nor the default combat mechanics impose restrictions on handedness for this weapon attack.

Weapons with the two-handed property only require two hands to make attack rolls. When you're not attacking, you can carry the weapon however you want. For example, while casting a spell, you could hold the weapon in one hand, and free the other hand for the somatic components (if any).

Just as your action and bonus action do not happen simultaneously, this does not imply that the Eldritch Knight is attacking while casting. They occur on the same turn.

Thus an Eldritch Knight could first cast a cantrip (using their free hand if necessary), move, then grab their weapon with both hands, and then make their attack roll (as a bonus action). All in one turn.

Answer 2

First, the Eldritch Knight's War Magic feature states

War Magic

Beginning at 7th level, when you use your action to cast a cantrip, you can make one weapon attack as a bonus action.

1. Yes, you can take an attack action with the longsword in your main hand as a bonus action.

2. The wording of the War Magic feature doesn't specify melee or ranged, only that it must be a weapon attack. So this is also allowed (with one condition, will explain in question 3).

3. For this question to be answered, we have to look at one of the Basic Spellcasting components.

   Somatic (S)

   Spellcasting gestures might include a forceful gesticulation or an intricate set of gestures. If a spell requires a somatic component, the caster must have free use of at least one hand to perform these gestures.

If you want to use a short/longbow or a two-handed weapon, you must meet at least one of the two criteria:

Option 1 - The cantrip must not have a somatic component. Some examples of this is Lightning Lure, or Green-Flame Blade.

Option 2 - You have the War Caster feat which will allow you to make the somatic components even when equipped with two-handed weapons.

As for versatile weapons, they are only considered two-handed weapons during the action when you are making an attack using two hands. While you are casting, it is considered a one-handed weapon.