An adjective for someone who speaks in a way that he can get whatever he wants by using his talking skills

I was thinking of "Eloquent", "Fluent" or "Persuasive" but feels like it’s not what I want because the word I’m looking for isn’t about how many words you know, you can be eloquent but your choice of words isn’t that good.

I’m looking for a word to describe someone who is eloquent and smart at the same time. Like an expert lawyer talking to a judge.

"Persuasive" is the closest word to what I want but you can’t tell your team of sellers "try to be persuasive with the customers". It’s like selling them fake products.

I want my team of sellers to be _____.

Something like Christoph Waltz in "DJANGO UNCHAINED" and Leonardo dicaprio in "The wolf of wall street"