Reddit mentions of Fenix Flashlights E35 900 Lumen Flashlight, Black

900 lumens, 1x18650, $35-$45:

Solarforce L2P

Nitecore EC20

Fenix E35

Oh I must have misread your post. I thought the tail-switch was a must. The S10-L2 is a good light but it uses CR123 batteries which costs $1.25 a pop online (a lot more in a store) so depending on use it could get costly. They make rechargeable batteries (16340 Lithium Ion) but the these have about 70% the energy of a CR123 battery so you'll have shorter runtimes which is the biggest complaint of this form factor. Plus it'll be another $10 or so for these items although it'll be cheaper in the long run vs CR123 batteries. 400 lumens for 1.25 hours might seem good but runtime it to how long it takes to get to 10% of initial output (in this case 40 lumens). Here's a review of the S10-L2 if you'd like to see the runtime graphs.

There's additional options I can give you but I need to figure out what battery for you want. A high capacity 18650 battery has the energy of about three CR123 batteries or five 16340 batteries. I guess what I'm saying is that although I EDC a CR123 light because of it's compact size, I wouldn't EDC it if it was going to see heavy use which I'd switch to an 18650 EDC light for those situations.

The S10-L2 is a good choice still but might not have the runtime you're hoping for depending on what more you use the most. The Fenix EC35 which uses an 18650 battery will give you much better performance at the same price point. I can help you with a cheap battery and charger for any of these items.

https://www.amazon.com/dp/B00ITFKQ7A/ref=cm_sw_r_awd_VjDTub0F28265

Here it is

Assuming you're in a "heavy disarmament zone" like England or too much of the rest of Europe, by far your best option is motorcycle gloves with armored knuckles. You can use them as direct offensive weapons (no different from brass knuckles) or as defense, punching at the hand holding a knife for example.

Failing that, the other way to get a "brass knuckles" effect is to carry a good small flashlight, something fairly powerful if possible. In the US we can now get very potent small lights in the 600 lumen or more range, complete with a strobe light setting for use as a stunning/blinding weapon at night. I don't know if those are as common in Europe. The ones sold in the US are marketed mainly to the legal gun carriers because we believe it's vital to have both a gun and a flashlight since most trouble happens after dark and it's morally wrong to shoot at something you can't see. So every gun shop has potent flashlights and the 3v Lithium batteries that generally drive them (known here as a CR123). (Most gun shops have an entire jug of CR123s by the cash register.)

This is a good example of what I'm talking about:

http://www.amazon.com/Fenix-Flashlights-Lumen-Flashlight-Black/dp/B00ITFKQ7A/ref=sr_1_3?s=hardware&srs=2591774011&ie=UTF8&qid=1416786955&sr=1-3&keywords=fenix+flashlights

This one is nice because it doesn't have a "jagged" business end that makes it more obviously a weapon, but despite that lack it can be used as a "bashing stick" along these lines"

https://www.youtube.com/watch?v=6uIUXZYDmL8

Do a youtube search for:

Kubaton Techniques

...there's a ton of stuff out there. This basically the Asian version of brass knuckles, also known as a yawara stick.

https://www.youtube.com/watch?v=2i5jU847hV8

This is about as good as you can get with a pair of standard AA batteries:

http://www.amazon.com/Streamlight-88033-Tactical-Flashlight-Batteries/dp/B003GXF9OA/ref=sr_1_3?ie=UTF8&qid=1416791889&sr=8-3&keywords=streamlight+flashlights

Not as good at "blinding" but not bad and still a very good whacker at both ends.