Once liberty was surrendered to tyranny, it could be smothered for centuries before its flames again sprang to life and brightened the world.
When you are willing to meekly sacrifice your ultimate value, your life, the only one you will ever have, to any thug who on a whim decides to take it from you, then you can't be helped. You may be able to be rescued for one day, but the next day another will come and you will again willingly prostrate yourself before him. You have placed the value of the life of your killer above your own.
When you grant to anyone who demands it the right of life or death over you, you have already become a willing slave in search of any butcher who will have you.
Only you can achieve self-worth for yourself. Any group offering it to you, or demanding it of you, comes bearing chains of slavery.
Evil grants no mercy, and to attempt to appease it is nothing more than a piecemeal surrender to it. Surrender to evil is slavery at best, death at worst. Thus, your unconditional rejection of violence is really nothing more than embracing death as preferable to life. You will achieve what you embrace.
If you are unwilling to defend your right to your own lives, then you are merely like mice trying to argue with owls. You think their ways are wrong. They think you are dinner.
Generosity is fine, if it's by your free choice, but a belief in the primacy of self-sacrifice as a moral requisite is nothing less than the sanctioning of slavery. Those who tell you that it is your responsibility and duty to sacrifice are trying to blind you to the chains they are slipping around your neck.
There is no greater value than life - and that's what you partially recognize by your confused notion of granting mercy. Their conscious, deliberate act of murder takes the irreplaceable value of life from another. A murderer, by his own choice to kill, forfeits the right to his own life. Mercy for such evil is nothing short of excusing it and thus allowing evil to prevail - it codifies the taking of innocent life by not making the murderer forfeit their own guilty life.
In trade between willing parties who share moral values and who deal fairly and honestly with one another, compromise over something like price is legitimate. In matters of morality or truth, there can be no compromise.
Freedom must be won, but then it has to be guarded...