noun
bold move; daring technique; powerful move
Originally from sumo and judo for a decisive, high-risk technique. Now also used figuratively for any bold or ambitious action.
彼は土俵際で大技を繰り出した。
He executed a bold move at the edge of the ring.
新製品の発表は会社にとって大技だった。
The new product launch was a daring move for the company.
小技 means a minor or subtle technique, often used in contrast to 大技.
Compound of 大 (big) and 技 (technique, skill). The reading おおわざ follows standard kun'yomi compounding.