Used attributively to describe tools, stones, etc., related to the act or purpose of sharpening.
Used as an attributive noun to modify another noun (e.g., "sharpening kit")
sharpeninggerundium / partizip präsens Used attributively: e.g., "a sharpening stone"
sharpengerundium / partizip präsens ‘sharpening’ is used attributively (e.g., “a sharpening stone”) and thus functions as an adjective.