Jesus General, in your line of work, what are you, MI5 agent or something
With regards to "weapons" a mobile can be classed as a weapon now, your not "allowed" to use this, unless it is self-defence. Now what people class as self-defence is up to the court to decide.
I mean, look at that farmer, that shot that bloke to breaking in, and got put away for Attempted Murder. Also that Burgular that sued a women, because he cut himself on the window he broke to get in her house (Yes these are real stories )
People that take law into their own hands, are punished more nowadays. The judge would just see it as (your not above the law, you should of called the police ) and with less police available, etc etc.....I know, its wrong.
These are obviously quiet serious weapons you are talking about here, to shock people like that, and question you. They don't seem to be your average kitchen knife per-say.
In honesty, I would say, you do what you feel you have to do, but if your friends are raising an eyebrow, and they know you as a person, maybe you should raise any eyebrow to, and ask your self