I may buy a gun for when I volunteer at our local Democratic office. Seeking advice.

[Straw Man]

42. Knives are very deadly.

Not only that, but to use one effectively requires skill and physical strength. The notion that you should opt for a knife because a gun requires too much skill is laughable. I'm sorry, but that's the simple truth.

You should absolutely be ready to use your gun in the event that there is a knife attack. If you don't, people will die.

You should keep your gun concealed on your person, and no one should know that you have it. If it has to come out, it should be a surprise to everyone but you. Keeping it in a desk drawer is asking for trouble. First, there is the possibility of unauthorized access. Second, you may not be able to quickly access it yourself when you need it most.

For a relative beginner, a 9mm pistol is preferable to a .40 or a .45 since the recoil is more manageable. Furthermore, due to the slightly smaller size of the round, 9mm pistols generally have a larger ammunition capacity than .40s or .45s. For reasons of concealability and ease of shooting, you might even consider a .380 pistol.

A gun that is simple to operate is the quickest and easiest to learn. For that reason, striker-fired pistols like the Glock and the S&W M&P series are the most appropriate for beginners, IMO. Contrary to popular belief, you do not need a manual safety with this type of pistol. Manual safeties were designed for light-triggered single-action pistols like the 1911, and are not needed on double-action pistols or striker-fired pistols.

Get training. You may have to rub elbows with NRA folks to get it, but NRA-certified instructors are generally well trained and quite professional.

Get in the habit of practicing regularly. Try to shoot at least once a week.

Learn the three rules and follow them religiously.

--Keep guns unloaded until you are ready to use them. (Use includes carry.)
--Never point a gun at anything or anyone that you are not willing to destroy.
--Keep your finger off the trigger until the moment that you are going to shoot.

My short list for a new pistol shooter would include the following:

Glock 26 (9mm)
Glock 42 (.380)
S&W M&P Shield (9mm)
S&W M&P Compact (9mm)
S&W M&P EZ (.380)

I would avoid the tiny pocket pistols (Ruger LCP, et al) until you gain some shooting proficiency. They are easy to carry and conceal, but are considerably more difficult to shoot accurately.

Finally, realize that use of the gun is going to be a last resort and only a last resort. The gun is not going to forestall or defuse anything. The only situation it is going to resolve is the one in which everyone is going to die if you don't use the gun. Active-shooter training teaches "Run, hide, fight." If you can run, then run. If you can hide, then hide. If you can't do either of those, then fight. When it's time to fight, it's better to have a gun in your hand than a fire extinguisher.