Gladius Legis
Legend
If the problem is not getting to use it, just let them use it more - not invent brand new stuff to replace it, right ?
That's hardly the only problem with it. It's just the most fatal one. Even if you could use it more often, the main benefit is meh at best other than double proficiency on Perception and maybe Insight.
It's also bland. Like, simply saying "my Ranger's favored terrain is arctic" and having Natural Explorer's generic stuff working only in the arctic is all there is. There's just no meaningful expression of there being an actual arctic Ranger (or whatever other terrain) in the PHB class.