A simple question to answer, I thought, but so far I've been unable to find a reference that really clarifies it. The context for it is the Skill Expert feat in Tasha's Cauldron of Everything. Part of the feat description is given thus:
Choose one skill in which you have proficiency. You gain expertise with that skill, which means your proficiency bonus is doubled for any ability check you make with it. The skill you choose must be one that isn’t already benefiting from a feature, such as Expertise, that doubles your proficiency bonus.
I'm trying to determine whether that ‘one skill in which you have proficiency’ can include weapon proficiencies (eg. Martial Melee Weapons) or whether it is intended to be limited to things such as tool proficiencies, Acrobatics, and the like.
RAW and RAI answers equally welcome.