You’re right. Google doesn’t always cut it when it comes to image searching. It used to be the best for this stuff. Now? Not so much. You could always try Bing. That produces different results simply because their content filtering isn’t so aggressive. Google has a bad habit of excluding perfectly harmless content, treating it like it would porn. Google has become really worthless for a lot of topics. You really have to type in a very specific sort of image that they would curiously deem NSFW.
When all else fails, start with the source material and work from there. If, for example, you’re looking for a weapon from a cartoon, find some video from it and break it down into its still frames. Alternatively, you could get some “art of” books to use as your starting point. So, if you’re making something designed to fit the Zelda or Final Fantasy worlds, you could buy one of their many books, which are all great btw.
If you’re looking to create something “in the style of” a particular subject, well, you’re going to have to do some dissection and reverse engineering. It goes back to the old proverb, “Do not seek to be like the masters of old. Seek what they sought.” If you can figure out the logic and defining qualities behind the original design then it’s easier to create something in the same spirit.
One last trick. If you’re looking to create something totally bizarre and original, kitbash and repurpose. Take Boba Fett’s ship, for example. It looks totally badass until you realize that it’s basically a greebled clothes iron flipped on its end. Hollywood is notorious for cobbling together unique weapons or fantasy vehicles this way. You can do the same thing with characters too, slapping together interesting shapes into the silhouette as your starting point.
There’s no perfect solution to what you’re trying to do. Sometimes image search works. Sometimes it doesn’t. That’s where it pays to be creative, deductive, and good at improvisation. Remember. People were creating weird stuff long before the internet.