Had a random Airship thought today.
Hydrogen airships tend to burst into flame. Other than the Runesmiths' rune of No Burn Plz, which could have any number of reasons making it unworkable, what do we have that can suppress fire?
Mathilde's Arcane Mark, Flicker.
There's a couple of ifs in the way, but if we learned to control it, and if it could be codified it in a way useful for large-scale enchantment, it would be a very low-magic solution to a problem that would ordinarily take large amounts of magic or engineering to solve.
Also libraries could be enchanted with it. Very practical.