I have been an antique knife collector for many decades and specialise in US military and US folders. First off even though these knives arent rare they are historic so tred lightly. Next dont "polish er up". A light balde cleaning with 000 steel wool and wd-40 should be all the cleaning needed. So the blade is stained, so what, those stains add caractor. The world is full of shiny knives and guns but in severe shortage of knives with the "been there done that" look. Next take all measures to stop any active rust as this is a cancer that will eventually destroy the knife. Now that my rant is over, I will answer your question.I have had good luck tightening old leather handled knives by generous amounts of a quality leather conditioner. This can be obtained online or a leather shop. It takes several applications and and a few months to recondition the handle. Be pantient.