Using a high-powered tactical light not only helps to detect and identify a threat at a greater distance, it can help slow or deter an assailant by impairing their vision, thus giving you the time to retake the initiative.
Blasting the threat directly in the eyes with 350 lumens of light at night may help hinder an assailant's vision, but 800-1000 lumens is much more effective, especially at longer ranges (e.g. 20ft). Factoring in the strobe function of the light will disorient the would-be assailant even more.
Tactical flashlights are great less-lethal tools for protection. However, keep in mind that you should never rely on just the tool (no matter what it is). Your mind is the greatest advantage you can develop, so learning tactics and the ability to adapt will give you a greater edge.
Situational awareness, knowledge of tactics (not just techniques) combined with the function and effects of specialized tools will greatly increase your chances of protection. Think ahead, protect yourself, and get home safely.