1) The abrogation of the civil law pertains to the CHURCH because Israel was a "Theocracy". The N.T. Church is not a nation nor is any nation today "God's representative". Thus the exacting of punishments against civil law belongs to the government. The term "wield the sword" is unquestionably a reference to capital punishment.
2) Again, Gen 9:6 pre-dates the Mosaic law and is a universal mandate to execute murderers. The reason given is because one has shed the blood of an "image bearer of God" and the penalty for committing this act against God and mankind is death. I am not about to try and reason against God's perfect will or reason. <img src="/forum/images/graemlins/wink.gif" alt="" /> Further, that mandate in Gen 9:6 was hardly something novel or new. Even Cain was privy to the punishment for murder and feared that his life was hanging by a thread for murdering his brother Abel. And how was it that he knew about capital punishment long before God specifically spoke of it to Noah? Because by nature, every single human being is born with the law of God written on their hearts and thus none are without excuse.
3) Convicted murders are no more or less needy of hearing the Gospel. It should be made known of their hopeless and helpless condition; not as a murderer though they surely be so, but rather that they are sinners before God and under his just wrath and condemnation unless the Lord should show them mercy and open their minds and hearts to the truth as it is in Christ Jesus and to give them repentance and faith. But their "need" does not abrogate their guilt of murder nor does it abrogate the command of God that they should be put to death for murder.
4)
You wrote:
but a repentant soul is spared the damnation from Him through the sacrifice of His son. Should this not be a model for us too?
First of all, Christ's vicarious substitutionary atonement is not to be diminished to where it is but a "model/example" for us. Charles Finney with his "Governmental Theory of the Atonement" erred thusly and is now in damnation for it (along with being a sinner without Christ).
Secondly, IF you really want to follow through with your suggestion then logically, YOU should give you life in behalf of a murderer, since THAT is what Christ did for His own. The penalty of death was Christ's sentence and He was not spared from it. The penalty for murder is death and someone needs to die. If not the actual murderer, then who would be his substitute? <img src="/forum/images/graemlins/scratchchin.gif" alt="" />
In His grace,