Well although some people in the 18th century did not look after their tools, I think there were a lot more that did. The passage regarding Gist and Washington comes to mind. These two set off alone in the wilderness with only one blunt hatchet and no means of sharpening said hatchet. How dumb can you get! It always amazes me that seemingly educated people make so many bad mistakes, especially when their lives may be at stake.
There were whetstones and metal files commonly available during all periods of the 18th century and earlier. A smart person would carry one or both of these items to keep their knife and belt axe/tomahawk sharp and in good working order. Here are some examples below.
An early Barlow clasp knife, probably 17thc.-18th century, with a whetstone.
The above images are from: finds.org.uk.
Honing and whetstones. Notingham University Museum. Photo By Robin Aldworth
Basing axe and whetstones. A basing axe is used to roughly shape the whetstone at the quarry.
A whetstone from my collection. This one came from a creek bed.
An 18th century whetstone in a wooden holder.