The tung oil I've used in woodworking dries with a sheen. Wouldn't that make it a little artificial looking when used on deadwood?
I avoid using wood hardener on deadwood as a preservative. Aside from the kind of unnatural looking shiny finish, wood hardener doesn't provide much preservative protection.It is meant to plasticize soft punky wood so it can be worked--it doesn't seal it, per se. I had one older rose with a six inch dia. trunk that was decomposing badly. I tried to "preserve" it using wood hardener. The result was two years after I began treating it, the trunk simply caved in. There was a 1/2 inch shell of hardened wood where wood underneath had simply rotted away--water had seeped through...