Where did the phrase "to come in handy" originate, and what exactly does it mean?
My understanding is that it essentially means to be useful. Is this correct?
As far as origins, I have no idea. Etymonline did not seem to know, either.
Etymonline.com says of handy:
To come in handy means something will be handy or useful in the near future, that it will become handy.
Come in handy
The earliest verifiable examples I found in Google Books are both from 1843.
First, in a "Weekly Journal of Gardening" column of The Gardener and Practical Florist:
We can also find some slightly early uses of the similar to come handy. It was once used similarly and as often to come in handy, but lately has become rarer.
An October 1824 The London Magazine prints a letter from summer 1821:
It hails from the 1800s (per Dictionary.com) and it means:
Here is the Ngram graph of its usage:
This led me to an 1840 usage of the expression:
It looks like it evolved from the Middle English hende, which carried both the meaning of "readily accessible" and "useful" as well as a host of other definitions, which itself rose out of the Old English/High German gehende, which, interestingly enough has more or less the same definition as "handy" does today. I just wrote a paper on it, but I wasn't able to find any confirmation, so this may as well just be treated as food for thought or one of many possibilities. As it happens, hende was used in Middle English literature as of the late 13th/early 14th century, so the evolution into "handy" could have happened at any point between its own recorded uses and then.
A useful implement close at hand is how I would understand something handy. Most times we have to draw inference from precedents and usage rather than hard and fast definitions.
Early use of the phrase seems to indicate such an intention on the part of the authors, as well.
Sometimes, though, come in handy may have been used in one or the other of the meanings alone: useful or accessible.