For long range, the DCAU Watchtower. Even if the words "Binary Fusion Generator" (note the acronym) don't mean anything to you, you get access to the friggin' Justice League. And if things go really pear-shaped, you can always drop it from orbit on your enemy's head.
For short range confrontations, a serrated obsidian blade with an olive or Bois d' Arc handle. An obsidian blade, properly made, is orders of magnitude sharper than surgical steel, and the serrations let me inflict maximum damage with minimal effort.
And for conflicts in between? We'll, there's always Ye Olde M14.