The words for 'easy' in most spoken languages and signed languages are kind of easy like "easy" in English, "facile" in French, "einfach" in German, "lehko" in Ukrainian, "laykht" in Yiddish, and and this one in ASL.
Why? Maybe not to contradict with the concept itself?
ASL sign for EASY
"What is the sign for 'easy'?"
Definition: Achieved without great effort; presenting few difficulties.
How is it easy to learn sign language? See the comics below for a short answer or the article for a long version.
A common misconception is that some hearing people think that learning a signed language is easy. Sure, for the first few signs or several signs (no different for any spoken languages) up to the beginner level. After that, good luck if not persistent.
Then after that, you sweat all the way to the interpreting level. This fluent level is about halfway away from the native level. It's still difficult to interpret for a native-level, fast-talking, culturally Deaf who was born into and grew up in a Deaf family, Deaf community, and Deaf schools which is a minority of a minority. :)
Contrary to the assumption, signed languages are not easier to learn than spoken languages.