Here is the runner-up:
The ability to speak, in conversation, in complete sentences, not in broken phrases.
And here is No. 7:
The ability to capitalize speedily and accurately in one’s writing.
And here is No. 9:
The ability to think quickly in an emergency.
And here are some more, all within the first hundred:
The ability to refrain from marking or marring in any way a borrowed book.
An attitude of democracy rather than snobbishness within a conversation.
Familiarity with the essential stories and persons of the Bible.