Wizards get scrolls and potions. They get cool wands which give them new tricks at the same time the fighter gets, at best, a +1 sword. They actually can eat the scroll and learn its contents, a permanent breadth of power increase.
Clerics get the scrolls and wands too, albeit without the permanent personal boost. And potions, natch.
Druids, bards, paladin, rangers ditto.
It’s fun to hand out one-use and, to a lesser degree, limited use items. They are useful treasure which players want to track and find a situation to which they apply, not an incremental treasure increase.
But potions, always potions? Boring, and helpful to casters too.
Archer-types get enchanted arrows or bolts or bullets. Pretty cool.
But what of the poor melee character? Drawing a weapon is sufficiently expensive that, while I considered obsidian daggers or spears, consumed as they strike at the moment their power is unleashed, it’s not really what I want. Requires a golf bag to keep track of it all.
Now, poisons and a few similar alchemicals are close; they still encourage the warrior to use their weapon but layer effects on top, and are single use, and small.
Let’s talk kata: semi-ritualized practice moves. Perhaps fighter “scrolls” unlock these techniques. But once you have access to Falling Eagle Strike, it feels like you should either always have it available, or else go play 4e. You could do something with concentration or something to ensure just one per scene, but it’s hard to make them really feel 1-use. Scrolls got around this with magic; the words fade from the page as read, and the magic is in the object, not just the movement. (Cynicism: yes, this is the 4e way out; in my defense I’m willing to call it magic!)
Can we use that? Kata-scrolls, when read and their rituals performed during a short rest, give some benefit that lasts until used or replaced with a new one, which is semi-magical and personal? I might allow passing a scroll around a group; a large number of people might benefit from a single training session, but a given individual cannot spam the same scroll continously once used.
Now, I happen to have access to a conversion of the maneuvers from the Book of Nine Swords from 3.5e. I’ll probably use those as my kata.
However, just within 5e core, you might hand out something like superiority dice (nonrefilling) and a maneuver, or a handful of bonus sneak attack dice (also non-renewable, can only spend a few per attack), freebie advantage dice, reactive stoneskin or blur or misty step or other combat magic, ki points and something to use them on, etc.