However, I was under the impression that the tagging system is here to make searching easier and more accurate.
First of all, cynical posts don't do much to help your standings so I highly discourage them.
Say we implement the "polearm" tag. It would only begin to snowball. Daggers, since they're not as long as swords? Magic Staffs for mages? But then we'd have to implement magic wand since of course, wands aren't staffs.
The point is, simplicity is the key here. An over abundance of specific tags is only going to become tedious, troublesome, and most are just unnecessary for the number of images they embody. We don't need 5000 tags for specific types of clothing, nor do we really need 50 tags for specific weapons. It would never end and then the system would just collapse on itself.
Searching under "weapon" pulls up 368 pages of results. And that will just grow. With the maximum image viewing limit at 15 images per page, that's quite a lot to go through.
If you think that's bad, try the "long hair" tag.
Unless I'm mistaken and there's a way to EXCLUDE a tag from a search
There is no such function yet. At least, not that I'm aware of.