Hello and thanks for your valuable support!

I have 3 questions (apologies if already clarified elswhere):

Apart from DM's options,

according to the "Sage Advice Compendium" a feature (and so any item) is magic if it answers to one ore more of the following guidelinens/questions:

1. Is it a magic item?
2. Is it a spell? Or does it let you create the effects of a spell that’s mentioned in its description?
3. Is it a spell attack?
4. Is it fueled by the use of spell slots?
5. Does its description say it’s magical?

Here are my questions:
1. If an attack in the Monster Manual 2025 has "the name of an item" (new Death Knight's "Dread Blade"), but does not answer any of the previous 5 questions, is it a magic item or just a item (mundane for the wielder)?
2. If is Magic, then can it be used as a magic item by anyone who takes it (e.g. the Dread Blade necrotic damage remains)?
3. If an item is described as "created by a God", but is still NOT compliant to any of the 5 criterias above, is it intrisecally magic because imbued by the power of the Wave thought god's act of creating such an item or is a DM's option?

Thank you!

I'd like to get second opinions+ here, but I'd say, in general, if the description doesn't say it's magical, then it isn't.

Regarding the second question, this info from the MM is relevant:

Gear

Monsters have proficiency with their equipment. If a monster has equipment that can be given away or retrieved, the items are listed in the Gear entry. The monster’s stat block might include special flourishes that happen when the monster uses an item, and the stat block might ignore Player’s Handbook rules for that item. When used by someone else, a retrievable item uses its Player’s Handbook rules, ignoring any special flourishes in the stat block.

[...] Equipment mentioned outside the Gear entry is considered to be supernatural or highly specialized, and it is unusable when the monster is defeated.

Equipping a Monster with Other Items

You may equip monsters with additional gear however you like, using the equipment chapter of the Player’s Handbook for inspiration. You decide how much of a monster’s equipment is recoverable after the creature is slain and whether any of that equipment is still usable. [...]

1. If an attack in the Monster Manual 2025 has "the name of an item" (new Death Knight's "Dread Blade"), but does not answer any of the previous 5 questions, is it a magic item or just a item (mundane for the wielder)?

- In general no, if it doesn't say the monster's attacks are magical then they aren't however a DM can overrule this.

2. If is Magic, then can it be used as a magic item by anyone who takes it (e.g. the Dread Blade necrotic damage remains)?

- In general no, monsters are designed differently from PCs it is almost always a terrible idea to allow PCs to use monster attacks -> there is a reason Shapechange and True Polymorph are 9th level spells!

3. If an item is described as "created by a God", but is still NOT compliant to any of the 5 criterias above, is it intrisecally magic because imbued by the power of the Wave thought god's act of creating such an item or is a DM's option?

- Items created by a God are beyond magical, they are not "non-magical" but they also are immune to things that specifically target magical items (e.g. unaffected by anti-magic).

Got it, THANK YOU! :-D

the SAC entry is still the best guidance we have to go on, although with the fundamental changes to game and monster design that have come with MMM and after, I do feel like that guidance is due for an update.

The classic SAC answer from 2014 has been updated (and extremely simplified):

How do I tell if something in the game is magical?

Game text explicitly states if an effect is magical. Effects created by spells and magic items are always magical. See “Magical Effect” in appendix C of the Player’s Handbook.