Quote from K.P.A.
I would have ordered him to put down the knife. If he didn't I'd have shot him and suffered the consequences of the "no guns on campus" rule.
We were not there and cannot say how introducing other variables would have effected the outcome.
A few things to think about
1) Look at shooting statistics. I will use police officer involved shooting information.
2) Most officer involved shootings occur at very close ranges. Contact to several feet in many cases.
3) Depending on the statistics, officers hit what they shoot as as low as 10% in some cases. I have seen statistics from around 10-50% depending on the source.
4) Police officers are commonly shot and killed with their own weapon. Meaning, an assailant takes possession of a trained officer's gun and uses it on the said officer.
These are not great statistics for trained police officers, let alone somebody from the public. Assuming you are well trained, the statistics are still against you.
Who's to say shooting would have resolved the situation? Would other people have been killed or injured in the process from bullets that miss the mark, would the attacker obtain control of your gun and use it to create additional mayhem, or would you have saved the day? It is hard to say.