This is why you must take extreme precautions when you create a raneword. Double-check and triple-check that the item's form is correct- for D2R Items example Insight, for instance. Insight runeword can be created in staves and polearms however not spears. Lastly, put the runes out in the correct sequence before socketing them into the item.
There are some nuances with regards to weapon and armor types that you should be aware of. "Body armor" is only for items placed on your body. General "armor" includes shields, boots, gloves, helms, etc. Hammers cannot be used with runewords intended for maces. "Melee weapons" are not included in ranged weapons, like Crossbows, bows or even crossbows. Orbs are not also considered melee weapons.
When you create runewords, a lot of have different statistics that decide how good of a roll you've made. A perfect runeword roll is always worth more than an imperfect roll. Also, using the best runeword base (an item that has sockets) possible is always suggested. For instance, if creating a runeword for use on a mercenary use the Ethereal base. Mercenary armor and weapons don't diminish in durability, meaning you'll get the stat boost from the Ethereal property without worrying about it breaking. Every little boost in stats is worth it to the game Diablo 2: Resurrected.
Runewords can be fitted to any character. They'll be rewarded with the runeword's bonuses unless otherwise stated. It is possible to put, say, a Beast runeword to buy diablo II resurrected items the Sorceress and give her the ability of turning into an Werebear. This lets you play with different builds and gives players a variety of choices for engaging playstyles.