Musician Paul Di’Anno, former lead vocalist of Iron Maiden, took a slew of secrets to the grave when he passed away on Monday at 66. Hidden truths include a “knife fight” he got into with his girlfriend, a satanic tattoo, and a firearms defense among others, RadarOnline.com can reveal. A statement posted on Di’Anno’s official Facebook page — shared by his family and record label, Conquest Music — announced he passed away at his home in Salisbury, England. The news came after the heavy metal singer struggled with a weakened immune system following a sepsis infection nine years ago. Di’Anno had …