knowledge angel
n. An individual with extensive knowledge in one or more aspects of business who helps a start-up company that lacks expertise in those areas.
Examples
2001
QCED believes that companies like Phoenix — small, post-start-up, high-growth tech firms — are largely ignored by traditional academic research and business models. Success stories do exist, but entrepreneurs struggle to find ones that apply to their situations. And they rarely have time to waste.

That's where QCED hopes to come in. The firm has a network of 50-plus "knowledge angels" — advisers from across Canada who lead high-growth firms. Companies can also sign up for services such as mentoring, interim management and venture capital coaching.
—Andrew Wahl, “Thanks for the lift,” Canadian Business, November 12, 2001
2000 (earliest)
That helped cement a project for the Queen's centre — to create a network of 'knowledge angels,' proven corporate players who could fly in and aid an early-stage company having difficulties or needing help in an unfamiliar area.
—Daniel McHardie, “'Knowledge angels' aim to answer prayers,” The Globe and Mail, October 03, 2000