un-

un- is an affix that makes the noun smaller, either physically or mentally, like mini, or micro.

eg: jre -> unjre (tree -> mini-tree/sapling).

Because of its nature, it can be used to both ridicule and compliment: unwu (small you) can be an insult, being that your calling them small or irrelevant, or a silly nickname.

It comes from the number 'un' (one) and it formed as an affix as the comparison of how small the number is.

-seon

-seon is an affix that describes the process most commonly used / or most relevant with that object (though the process meaning can change person to person)

Eg: eron -> eronseon (Iron -> Smelting, Metallurgy), fer -> ferseon (Fire -> Cooking, Burning)

It comes from the affix -tion/-sion in english.