Open-handed means generous in giving. An open-handed host, open-handed with money, open-handed to a fault.
The image is a hand that does not close round what it holds. Open-handed also describes a blow with a flat palm, which is a very different sense.
1adjectiveopen-handedGenerous in giving.
“He was open-handed to a fault and left nothing behind.”
open-handed is a quality.
Open plus handed, from the image of a hand not closed round its contents.
From open + handed.
Etymology from Wiktionary, CC BY-SA