Third-degree assault is considered a Class A misdemeanor. It is defined as negligently causing injury using a deadly weapon or dangerous instrument.You will face a change of assault in the first degree if with intent to cause serious physical injury you seriously injure another person with a deadly weapon. Facing Assault With a Deadly Weapon Charges in New York? Call Lebedin Kofman LLP now at (646) 663-4430 to discuss your case and legal options. Assault with a deadly weapon is not a civil complaint - it is a criminal complaint. You can file a criminal complaint with local law enforcement. Criminally Negligent Assault, PL 120.00 (3). You will face a change of Assault in the first degree if with intent to cause serious physical injury you seriously injure another person with a deadly weapon. Assault with a deadly weapon is usually one of the most serious offenses, next to manslaughter and murder.