Grace and Steel: Catholic Influences in the Art of the Navaja explores the moral and spiritual world behind one of Spain’s most iconic weapons. Far from being merely a tool of street defense or dueling pride, the navaja emerged in a culture deeply shaped by Catholic theology, ritual, and moral codes. From the battlefield ideals of the Reconquista to the whispered prayers before a blade was drawn, this book traces how faith and fighting were never fully separate in Catholic Spain. It delves into the ethical boundaries of self-defense, the ritual undertones of dueling, and the quiet acts of resistance carried out by women armed with folding blades. Along the way, it shows how confession, conscience, and the ever-present weight of sin shaped the way the navaja was used—and remembered. Boldly original and steeped in historical insight, Grace and Steel reclaims the sacred tensions between honor and humility, survival and sin, tradition and transcendence. It is a study of the knife not merely as a weapon, but as a moral threshold.