How is the magic weapon level of Javelin of Lightning decided?

Question

https://roll20.net/compendium/dnd5e/Magic%20Weapon#h-Magic%20Weapon

Here "magic weapon" is described as a spell, and the effect it has on the weapon is decided through what spell slot you used to cast the spell.

You touch a nonmagical weapon. Until the spell ends, that weapon becomes a magic weapon with a +1 bonus to Attack rolls and Damage Rolls.

At Higher Levels: When you cast this spell using a spell slot of 4th level or higher, the bonus increases to +2. When you use a spell slot of 6th level or higher, the bonus increases to +3.

https://roll20.net/compendium/dnd5e/Javelin%20of%20Lightning#content

Here it says

This Javelin is a Magic Weapon. (.....) The javelin's property can't be used again until the next dawn. In the meantime, the Javelin can still be used as a Magic Weapon.`

But how is the javalin used as a magic weapon when there's no text to describe it?

Should we assume it is a magic weapon lvl 1, and I should just add +1 to my attack and damage rolls?

This answer on stackexchange: What is the casting level of magic items? eg, Javelin of lightning

Explains that the spells from a weapon should be cast on the lowest possible level, but I'm not sure if that answers my question well enough

Answer 1

"Magic Weapon Level" is not a thing

Unlike previous systems, there is no requirement that a magic weapon have a +1 minimum bonus of any kind. The Magic Weapon spell does give a +1 bonus, but magic items can have other bonuses. Flipping randomly through the DMG, I see that the Frost Brand (DMG 171) gives a bonus to damage but does not have an inherent +1 to attack and damage rolls, for example.

Therefore, once you use your Javelin of Lightning's special ability, it is a javelin with no bonuses to attack rolls and damage.

"Magic Weapon" is an inherent, meaningful property on its own

A javelin that is magic but doesn't give any bonuses is still useful, however. For example, the Lich (MM 202) is immune to

bludgeoning, piercing, and slashing from nonmagical weapons

But has no resistance to magic weapons. Therefore, you can use your javelin to deal normal damage to a Lich, where an non-magical javelin would deal no damage.

Many high-level monsters have this property, so having a weapon like this is not (totally) useless.

Answer 2

+0

A standard "magic item" doesn't have a bonus to hit or to damage. If it did, the description would tell you. It will bypass resistance to nonmagical damage, but it does not imply any other bonus unless your DM decides to rule otherwise.

Answer 3

The javelin doesn't give any bonuses to hit or damage because the text doesn't say it does: things do what the rules say, if the rules don't say it it doesn't do it.

When not using its lighting power it's the equivalent of a mundane javelin from the equipment list, except that it counts as a magic weapon. This means it overcomes damage resistance/immunity to non-magical piercing damage.

Answer 4

Javelin of Lightning has no "magic level" (e.g. +1), it only provides a bypass to magical resistance/immunity.

In addition,the majority of it's damage is from a saving throw, not an attack roll.

Things in 5e do what they say, no more and no less. (The Javelin of Lightning states DMG, 178)

When you hurl it and speak it's command word...each creature in the line [between you and the target] must make a DC 13 Dexterity saving throw...The Lightning bolt turns back into a javelin when it reaches it's target. Make a ranged weapon attack against the target. On a hit...

For the creatures in the line between you and the target, there is no "to hit" calculation made. It's simply a Dexterity Saving Throw. Only the target requires an attack roll as the lightning bolt returns to javelin form.

The Javelin is a Thrown weapon and is not versatile (PHB, 149), which means you use your Dexterity modifier when attacking (and any proficiency if applicable.)

The text does not state there is any modifier to add, so there is no modifier to add. It is simply d20+Dex Modifier+proficiency (if applicable).