Most thieves are lazy and cautious so the goal is to make it easier to just pass your house by for the next one to that end, the two best things are:
Window shades on all ground floor windows. Most burglars won't break into a house when they can't see what's waiting inside
A big dog. Doesn't even really need to be mean, just something to make them want to move on to the next house
Once someone's broken inside, you want a weapon that is instantly recognizable as a threat (so while hornet spray will work, you'll probably have to use it as opposed to just brandishing it). Chainsaw is probably perfect here, but the odds of injuring yourself would be insanely high.
Personally, I would go with something you can use to keep people at arms length - as strange as it might sound (and even stranger lying around in your bedroom) a pitch fork would be a good choice.