The Bach Flower remedy called "Rescue Remedy" is effectively calming for many animals. It's effective enough that Drs Foster & Smith sell it. A friend who wrote a first aid for pets class recommends it.
Cats can also take Klonopin & Valium, in doses which would surprise you (human sized).
Is the wound in the way of holding him by the scruff of the neck? If you can hold him by the scruff of the neck, you can work on him with the other hand.
I'm sorry, I don't think every wound needs extreme vet attention. When it's a small wound, I clean it myself & keep it open by cleaning it again every day while it heals. I treat my cat with GSI when he gets wounded -- I start it as soon as I see that he's got into trouble again. It's a natural antibiotic which is very effective. NutriBiotic makes an inexpensive gel which you will dilute with water. (Check their web site for instructions. I buy it from a local health/natural foods store or online from Vitacost.com.) I add it to my cat's wet food. It's very bitter -- to us. As far as I can tell, my very picky feline doesn't notice it -- I've decided cats must not have tastebuds for bitter. Not only does it keep wounds from getting infected, it has cleared up one which was already infected when I found it.
Overuse of antibiotics with animals is as serious & deadly an issue as overuse of antibiotics with humans. (In fact, at this point, the antibiotics put into the food of factory farmed animals is probably our biggest threat.)
Even a castrated tom cat will fight over territory, if a stranger comes into his.