Historical clue formulations

• Fortifies — 2024-07-18
• Toughens — 2022-08-10
• Braces — 2020-03-26
• Toughens — 2019-11-23
• Toughens — 2015-10-24
• Makes tough — 2013-10-23
• Braces (oneself) — 2008-12-02
• Makes hard — 2008-01-29
• Makes tough — 2007-09-24
• Braces (oneself) — 2006-11-27
• Braces — 2005-03-05
• Fortifies — 2003-01-24
• Toughens — 2002-01-17
• Renders unyielding — 2000-06-14
• Girds — 1995-08-11