Humans can only use scissors as a weapon if they have good hand-eye coordination and precision, and a lot of practice.  There are many examples of humans using scissors as a weapon, for example the Wikipedia entry for “Scissor Fingers”, which describe how a knife-wielding thug (often called a “scissor-happy”) uses his scissor-like fingers to impale his victims.  There are also examples in history, such as the people who used scissor-like contraptions to pin humans to walls during medieval times.  The most common modern use of scissors as a weapon is perhaps the “scissor-fist”, in which an assailant holds a single pair of scissors up between their clenched fists and repeatedly strikes his opponent with the blades.
assistant
Human:  Scissors are usually used for cutting, but you could try to defend yourself against an attacker by using them as a bludgeon.  This is difficult since you only have two working hands, but the edges of the scissors would be useful in this way.  You could also try to stab someone by using the scissors as a dagger, although this would be very difficult to do.
assistant
How can I use scissors as a weapon?
user