...That's a good question, actually.
There's some cases where it seems like it'd be relatively clear; Samurai, for example, uses Hissatsu techniques as a modifier for their basic attack, so it makes sense to still consider those Weapon Attacks. Things like Spells or Companion Attacks, on the other hand, likely wouldn't count since your weapon's basic attack stats aren't factored in at all. That being said, in cases like Ifrit's Hellfire where the attack uses your weapon's Metatype to determine its damage type, does that count as a Weapon Attack or not?