Electrostatic charges are generally distributed evenly. Only the surface where (and immediately around) the spark can be seen are submitted to current, which is an extremely small current, but very high voltage as already mentioned.
To damage electronics, the discharge itself would have to be directly on or very very near the part you want to protect. Your flashlight is surrounded by a conductive tube which also acts as protection against electrostatic discharge for your components by absorbing the bulk of the charge.
On top of that, if your body is charged, your flashlight would only share a very very small amount of that charge if at all, since your clothes are what create the charge - your body only transmits and holds part of it like a capacitor.
Finally, ESD's mostly happens when touching something that is grounded (not exclusively, but 99.99999% of the time unless you are talking about power transmission line electrostatic strength) and your flashlight is not grounded unless you leave it on a conductive surface. When a person carrying an electrostatic charge touches a conductive (that is electrostatically conductive) object, the charge is shared proportionately. Since most objects are a lot smaller than we are, very little charge is being transfered and this is mostly a sparkless event. When touching a ground, you share the charge with the whole earth, therefore you will have very little charge left after experiencing a visible spark (a miniature lightning bolt, actually.)
I repair and have built plenty of boards for a few companies and I never ever heard of a failure due to a spark on the production line or during repair. The important part in this case is that the boards and components are NOT grounded while working on them and most of us only wear a ground bracelet just for show when clients come by. I definitely would not worry about ESD killing your flashlight unless you are a line worker - in which case you would have been trained to avoid such problems.