To arrive in more quantity than can be met. Overwhelm is not weakness; it is a limit being exceeded.
Middle English over + whelmen (to turn upside down, submerge), from an Old English root related to hwelfan (to overturn, vault over); to be overwhelmed is to be turned under by more than can be met.
The arrival of more than a limit can meet. Naming a state overwhelmed says something true about the limit, not about weakness in the one who reached it.