The only time we go 2-on-1 is for 'fun' with the kids. The odds of a 2-person assault are very low and extremely low when you factor out the ones where the person attacked either knew the attackers or was involve in the incident in some way. And training to a good level of sufficiency on one attacker will give a person a chance against two by using the same skillset.
A two person attack is definitely in the avoidance and SA category. Avoid at all costs if possible.
As far as carrying a weapon, it is on the person to train and to stay polished on the use of said weapon. I live in an open carry state and depending on what part of the nearest big city I go to I open carry. It is a deterrent. I carry All the time.
As a MA's school, we have a joint program with our city PD to train and qualify students (adults only of course) in firearms. And I take a 'awareness' approach on who is invited to take the program. If a person has neve been around firearms and has zero interest in having one, no harm, no foul. But if someone starts the program they are required to take the Bi-annually courses and invited to our monthly group firing range sessions. For obvious reasons, this is done on an individual basis to avoid liability on the school.