I generally buy wrenches in very good to excellent condition. Engraved initials are generally not additive. Sometimes, though, if the tool is in the range of uncommon to very rare, initials have to be overlooked. If some guy bought a great wrench 100 to 150 years ago with hard-earned cash, and wanted to ensure no one would steal it, sure, he would initial it.
My reason for collecting wrenches, in the first place, is to demonstrate the freedom of thought used by the man who designed the wrench. Freedom of thought is becoming less and less valued in America, and I think it is important to maintain a visible record of what it means. Wrenches solve one class of problems well - turning a threaded bolt or nut. But common men, working with their hands and minds developed thousands of different ways of doing that.