D&D is a game of exceptions; an attack can be special and not fall into either category: weapon or spell.

The rules tell you if an exception is happening. For example, the grapple described on p. 195 of the PH is called a special melee attack, not a weapon/spell attack. #DnD

— Jeremy Crawford (@JeremyECrawford) October 29, 2018

Hah! Does this mean you aren't answeing rules questions? This sounds like the final word of clarification for a game!

— Michael Phillips (@roninkakuhito) October 29, 2018

Many D&D players like to understand the intent behind the rules. And many groups like to dive into the details of the rules and abide by them. My rules answers support all of that. #DnD https://t.co/VbEgtjvRUd

— Jeremy Crawford (@JeremyECrawford) October 29, 2018