In most places that allow concealed carry, the intent of the attacker is not a criteria when evaluating the appropriateness. Rather, it is the reasonableness of the belief of the person using lethal force as to whether they considered themselves (or someone else) to be in danger of death or serious harm. This is very similar to the situation where a police officer is found innocent of wrong doing when shooting someone brandishing a toy weapon.

In general, anyone who is about to commit a physical assault, is clearly intent on causing harm. Whether that meets the needed criteria, according to a jury, will vary according to circumstances. One common piece of advice on a related subject is that given to women when considering their safety vis-vis ****. They are told to trust their instincts. If someone makes them feel uncomfortable--avoid contact. Is it a perfect test? Of course, not. However, this is really what we are talking about. Trusting your instincts. If someones actions are causing one to feel fear, then responding in a defensive manner is likely warranted.

Interesting anecdotal evidence, is that despite several million citizens with concealed carry permits obtained with the last 18 years, there has not been a rash (nor even a statistically significant number) of unjustified uses such weapons. So it would seem that the carrying of such weapons doesn't increase the liklihood of its use. Since those with the permits actually represent a smaller than proportional use of guns in defense than their population percentage they represent.

The short answer is that you don't know. However, there are thousands of incidents where normal citizens were able to successfully deploy concealed firearms to protect themself or others.