Copypasting some of this from when 🔫🦢 answerd the same question.

It’s my personal system tag. It’s so people who follow our blog know which system member made which posts.

We use emoji combinations because many of us are fictives with distinctive names, and we don’t want signing our names to make unrelated posts show up in character tags or searches.

💪🔫 specifically represents me, with the muscle emoji representing my tendency to be a big strong man (Chris Redfield, Nekomaru Nidai, Reiji Kido, etc etc) and the gun representing my continued existence as as a warrior.

You can find all our system tags in our pinned post.

Hope that answers your question, anon.