The man, who was under the care of a nurse, presumably started to behave erratically on 10 Monday evening, in feet, patient rooms, and taking pictures with his cell phone.
He then said he armed with two knives, the classroom teachers.
When the nurse, who was unaware he was armed, tried to convince him to return to his room, he would have attacked her with knives, cutting down his wrist, and his clothing.
She managed to escape in the classroom teachers with the help of an elderly male patient, who closed the staffroom door and kept the man confined to the room until the arrival of security and police.
Nurses at Blacktown Hospital have called for greater protection before.
Officers disarmed the 47-year-old man and arrested him. He remains at the hospital under police guard.
The safety of the staff of the hospital has been a controversial issue for years, with nurses walking off the job in protest in 2011, after a vicious attack on a staff member of the female sex.
Edith Castro-Rivera was stabbed by a hospital patient armed with a butter knife. He stabbed her 21 times and he broke his rib.
— with the wires