I'm a little confused by the meaning of the word "tactical" nowadays. I just don't get what criteria a light needs to fill before it's considered "tactical".
Though there are a few things that come to mind when that word is brought up, and I think this light sums it up nicely:
http://www.surefire.com/E2DL
Strike bezel for a last-ditch weapon(still better than your bare fists I bet you). It's more or less guaranteed that high mode is the first mode accessed if the light is turned on. 200 lumens which is sufficient to destroy "night adapted vision". Small enough to fit in a pocket, and a clip to ensure quick and easy access(with practice).
Though my idea of a "tactical" light would be a Surefire 6P with a pocket clip, crenellated steel bezel, and an SST-90 Direct Drive Single Mode running off one IMR 18650 battery.
Surefire lights are made rock solid, but they place little emphasis on the latest and greatest emitters. Which might make sense as 200 lumens would be more than enough "usable" light when it's pitch black. Therefore bored Surefire hosts with a custom drop-in would be a way to have the best of both worlds.
The fine print on Surefire marketing you have to pay attention to is where they say "night-adapted vision". In a dark environment with only BARELY enough light to see your immediate surroundings slightly(moonlight), the 200 lumens from a Surefire E2DL would be very blinding indeed for a short while. But on the sidewalk at night under a bunch of streetlights, 200 lumens of light wouldn't be as "blinding" as the light from the headlights of cars. Indoors would be a moot point, that ceiling light would put out more light than your little flashlight.
As far as blinding anyone goes, I don't believe you can completely impair a person's vision without the risk of permanent eye damage as well. Not to mention, it's not all that hard to stare directly at the sun even though it DOES cause eye damage, and I doubt anyone could describe it as "blinding". However, an interesting thing to note is that if there was a plane flying almost directly between you and the sun(but not so that it blocks the sunlight from reaching your eyes), you probably won't see it. Which is probably where the actual use of "tactical" lights is.
In a well-lit room when pointing my light at the mirror from about 15 ft away, the glare from the light more or less obstructs the view of the top half of my body. If there was a taser held in my other hand, I wouldn't be able to make it out at all, especially if it's held close to the light itself. I suspect there would be much more of an affect if it was done in a dark area from less than 10 feet away. It would be possible for a group to surround one person and hide their actions as well. Hell, if you hold the light off to one side of your body, you could even hide where you're actually standing(not so far fetched with the standard all-black uniform that cops use).