Only dangerous if used for their intended purpose...
Is it right to have an arms sale? Depends on what your selling, and who to.
Anybody who believes that the sale of weaponry contributes to democratic freedom is misguided. Although high tech systems make for impressive pictures, the international arms trade is all about small arms; guns, grenades, ammo, artillery, land mines, tanks. These items are the weapon of choice the despot, the tyrant, and the terrorist. All of the major military powers build their own kit - therefore, international arms sales' target audiences are, almost by definition, aimed at the ambitious third world gangster planning (or repressing) the next coup.
The arms industry brings in a lot of bling for the UK, but who from? People we should really not be supporting, that's who. Saudi Arabia, a theocratic monarchy in which it is illegal for women to drive, has been the UKs most consistent customer since 1997. Is it morally right to take their money? It's not going to be used on us (probably), but does that absolve us? What about selling arms to Bin Laden? Or Hitler? Would the boost to our economy outweigh the moral issue? I don't think so.
For those that say that weaponry is inert, and that responsibility lies with the user, I point out that these items have been designed for functionality. A landmine is stepped on and maims you. Napalm sticks to your flesh and burns you. A hollowpoint bullet expands in your body . Cluster bombs. Daisy cutters. The products of design, and far from inert. Could you justify selling equipment specifically designed for torture to the Saudis? How about a machine that skins humans ? What about a nuclear bomb? If not, your argument is invalid; you're conceding that there is a moral responsibility associated with the sale of the kit, but that the financial allure of the sale overrides any moral compunction.
Finally, whose money are you taking? Is it ethical to take the money from a despot when you know that the purchase of this equipment is taking food from the mouths of the poor. Can you really shrug your shoulders and say 'not my problem/If it wasn't us, they'd buy it elsewhere anyway'. This is also the argument used by opponents of civilian gun control with regard to acquisition of guns by criminals. If you sincerely believe this is logical, rather than just want to have a gun yourself, then, by the same logic, it's inevitable that Bin Laden or his ilk eventually get their hands on WMD, so we may as well sell it ourselves and make some money out of it.
If weapons really made the world safer, then arming everybody would result in less violence. Would you really feel safer if everybody had a gun?