Steely (adjective)

1. Resembling steel in hardness, strength, or color.
2. Having a character or manner that is unyielding or unemotional.

Origin:

From the word "steel" meaning "a hard, strong, gray or bluish-gray alloy of iron with carbon and other elements".

Examples:

1. His steely gaze revealed nothing of his thoughts.
2. She had a steely determination to succeed.
3. The sword had a steely edge that could cut through metal.
4. The steely blue color of the sky was a sign of good weather.
5. The athlete had a steely resolve to win the competition.