Steel and Razorblade

Steel

Steel is a rigid metal used in building structures, manufacturing, and weapons. Steel is made from iron that has undergone a refining process.
EX: Although the earthquake surprised even the most experienced seismologists with its magnitude, many buildings remained standing due to their rigid steel infrastructures.
EX: The invention of the steel sword greatly advanced warfare, aiding the user in defeating opponents more efficiently.
The expression nerves of steel is used to describe someone's presence who displays little or no emotion in high pressure or potentially dangerous situations.
EX: Though the task was the only thing keeping the employee from getting fired, she seemed to acquire nerves of steel and completed the paperwork to save her employment.
EX: The headmistress of the school seemed to have nerves of steel when dealing with the heated e-mails she was receiving over her decision to expel the student. She stood by her decision throughout, never doubting her intuition and sense of justice.

Razorblade

A razorblade is a sharp, metal edge that can be used to make very accurate and clean cuts. A razorblade is also commonly used for shaving hair. You could just say razor if you refer to the whole tool since the razorblade is just the sharp part.
EX: Using a razorblade to scrape the paint that had dripped onto the window's glass panes, Shelley wished the painters had been a little bit more conscientious.
EX: Since Hank had forgotten his razorblade at home on the washroom counter, he called the front desk to ask for a replacement.
The expression sharp as a razor means that someone of something is extremely quickwitted or very intelligent.
EX: The elderly woman had lived in the group home for a little over 5 years, but those who knew her best realised she was still as sharp as a razor.
EX: The young man, whose responses to the professor's interrogation were as sharp as a razor, always seemed to get away with the wildest pranks.