The student had just been expelled from school at the Birchmount Park Collegiate Institute on Monday afternoon, on Birchmount and Kingston roads, when he allegedly got into an argument with two other boys outside the school.
One of the three was stabbed by the other two and taken to hospital for treatment.
The director of the Birchmount Park Collegiate told parents in a letter that his injuries were not serious.
Investigators said they were initially looking for three suspects who fled shortly after the incident.
On Wednesday, police said they had arrested a 16-year-old boy and a 15-year-old boy in custody.
Both were charged with assault, assault with a weapon, dangerous weapons and a concealed weapon.
No suspect can be identified under the terms of the Youth Criminal Justice Act.
Both boys appeared in court on 1911 Eglinton Avenue East on Friday morning.
