She's on the ball.
This is an idiom meaning the person is quick thinking and fast to react to situations. You can use this for people who are quick with jokes, they are fast with comebacks. It can also be used to describe people who are always alert in work or in sport.
"You're always on the ball".
"You're on the ball this morning".
"You're always on the ball".（いつも頭の回転が速いね）
"You're on the ball this morning".（今朝は冴えてるね）
She's good at quick comebacks!
She's quick with the jokes!
She's good at snappy wisecracks!
I love how intelligent, witty and charismatic she is.
She is great with banter.
Charismatic- Being drawn to someones charm.
Banter- he playful and friendly exchange of witty remarks.
She is very erudite
She has great charisma, is mentally sharp and makes witty retorts
It seems that this person would make a great guest at any meal or party. Apart from her intellect it seems she also has a good sense of humour and it is often said of this type of person that they have 'great charisma,' which means they make a favourable impression on most people that they meet.
Erudite means having or showing great knowledge or learning:
"Ken could turn any conversation into an erudite discussion."
A retort = a comeback
"Ken could turn any conversation into an erudite discussion."（ケンはどんな会話でも博学な議論に変えることができる）
A retort = 返し
I love how clever and witty she is!
I like how she's always on the ball!
I like how sharp she is!
The most simple way of saying this is "I love how clever and witty she is". Witty simple means in conversations she is quick at making good jokes. A common phrase that we use in England for being quick and alert is "on the ball". Or you could describe someone as 'sharp' which refers to them being clever and mentally quick!
最もシンプルな言い方は "I love how clever and witty she is"（頭の回転が速く手返しがうまいところが好き）です。
"on the ball" は機敏で抜け目ない人を表すイングランドでは一般的なフレーズです。
Ms smarty pants
All of these expressions are common English expressions. Clever clogs and Ms smarty pants are meant to be playful banter directed at someone that knows something you didn't know or were slow at answering yourself.
As far as rapier wit goes, it carries the idea of cutting, sharp and cleanly. To have rapier wit, your comments would be sharp and somewhat sarcastic but at the same time playful. Always remember - Sarcasm is the lowest form of wit...BUT...wit is the highest form of humor!
"Clever clogs" と "Ms smarty pants" は、自分が知らなかったこと、あるいはすぐに答えられなかったことを知っていた人を冷やかす時に使われます。
"Rapier wit" は、コメントが辛辣（しんらつ）で皮肉もあって、しかし面白い人をいいます。
"I love how she's really clever and always makes witty comebacks"
"She is really on the ball with her intelligence and her witty comebacks"
"She has brilliant banter"
If you are asked what you like about a certain person, who happens to be female and you would like to explain that you like how she is very clever and can make witty remarks, you could say any of the following: "I love how she's really clever and always makes witty comebacks", "She is really on the ball with her intelligence and her witty comebacks" or "She has brilliant banter".
"I love how she's really clever and always makes witty comebacks"（頭の回転が早くて返しが上手いところが好き）
"She is really on the ball with her intelligence and her witty comebacks"（彼女は頭の回転が早くて返しが上手い）
"She has brilliant banter"（彼女は冗談が上手い）