If you are worried about knife and firearms being used against you - my best advice is for you to move to somewhere else.
The defense techniques against weapons all focus on controlling the hand, wrist and extended arm up to the shoulder. Speed, reflexes and correct judgement of opportunity and the situation is paramount. It is extremely dangerous to try and use unarmed techniques against an armed opponent. Unless your work involves this type of defense and your survival, I would rather discourage you thinking that you can overcome someone with a weapon.
Krav Maga focuses on quick brutal techniques, and is eclectic as pointed out - but it is stupid for normal people because they think they are super-heroes. It is ok for bodyguards, security people etc, but Krav Maga is very incomplete as a fighting style for unarmed combat. Also, a big part of TMA is about your inner personal motivation and integrity; Krav Maga and some other modern styles lack this aspect totally. What makes you survive a lethal situation is many times your character, not your fighting skills. Therefore I find Krav Maga mostly useless. When you want to learn combat techniques as a soldier, you might look into a number of efficient styles like combat Sambo, combat Jiu Jitsu, Hapkido and maybe Systema or Krav Maga.
Actually, Vladimir Putin is an accomplished black belt Judo practitioner and released a book last year. He also hold a "master of sports" title in Sambo.
Here in Brazil you would be dead pretty quickly if you go to some neighbourhood or stroll alone at times where you know you will be robbed - while thinking you can defend against armed thugs.
Self defense means surviving... you don't want to "blow up your account" with a gun in your face. Money management rules!
