I'm going to go a slightly different route than some of the other suggestions here.
Buck's custom shop does a very very nice job, and you get to pick exactly which materials you want. For blade steel you have the option of S30V, which may not have the panache of ELMAX, but nobody is going to poopoo the quality of S30V steel. It's damned good stuff.
You get to pick the handle materials, and even get it engraved. if he wants water buffalo then cool, rams horn, wood, etc... whatever handle is your preference, you can have. And I don't care what his buddy says, if the hubby is so rough on a blade that he's going to damage S30V, he's doing something wrong. That's a damned good steel.
There's something sentimentally very nice about getting to pick every single element of the blade, and there really is
practically no compromise in quality vs. some of the other knives with fancier steels.
Of course, there's nothing to say you can't get your own options AND the highest end performance. Big Chris already chimed in here, and he's really the go-to guy if you want something like you're describing. It's not cheap, but his stuff is worth every single penny and then some. Your husband would get something that says even more than a knife off an assembly line. It would be made by a true craftsman, and an excellent one at that.