Vexillarius

"A soldier chosen as a vexillarius is a standard bearer that carries the Vexillum, a military standard displaying the emblem of the Legion. The vexillarii provide troops with a rallying point and morale during heated exchanges, but rarely are seen in combat. These soldiers are given luxuries including firearms, superior armor and distinctive helmets in comparison to the standard legionary. https://fallout.fandom.com/wiki/Caesar%27s_Legion_military_hierarchy#Other_positions"

Starting out
The Vexillarius is essentially a Legionnaire Recruit, chosen to be a rallying point, and morale boost during battle. You should probably stock up on Healing powder, and speak with the followers to keep you in supply. This will ensure that you can keep wounded Legionnaires actively in combat.

Listen to the orders of your superiors, and attempt to position yourself well. If you're unsure where to set up, ask your superiors for guidance.

Being a Vexillarius
You should avoid combat as your fellow legionnaires will be looking to rally on you during combat. It might be best to alert your fellow brothers of this, and notify them if you're carrying extra ammo, healing supplies and the like. Work with the "Second wave" troops, such as Veteran Decanus who should be staying out of combat until the first wave are over ran.

Chain of Command
Caesar. Legate. Praetorian. Centurion. Veteran Decanus. Decanus. Veteran Legionary/Explorer. Recruit Legionary/Scout. Camp Follower.

Legion specific rules
Vexillarius has no real rank. They hold a flag and doot doot. 0. No female or ghoul legionnaires.

1. Stay within the Roman theme of naming. You’d be given a new name when you join the Legion.

2. No medicine save for healing powder, poultice, bitter drink and mushrooms for anti-toxin. Chems must be disposed of.

3. The Legion uses any equipment it finds, but would not keep items like medical technology, or techno-magic items, such as bluespace backpacks.

4. Legion ranks are defined by equipment. Survivors traditionally reform the hierarchy by taking the armor of their dead superiors, to assume their position.

5. Caesar’s Legion consider women inferior, this delegates them to support and slavery, rarely if ever do they accept a woman as worthy as more than a slave.

6. NCR are typically strung up on a cross when captured (and if it is deem fitting, they can be turned into slaves),as are chem users.

7. Men are to be trained as Legionaries, while women are to be trained as healers and farmers, as well as cooks.

8. Caesar's Legion is comprised of mainly tribals, meaning most of them do not know how to read, however the Centurions of war camps are typically somewhat educated.

9. Camp Followers are entirely loyal to the Legion. Playing them as anything but is grounds for a jobban. There are reasonable exceptions to this, such as overt abuse by the Legion, who should at least treat you as an asset.