I am looking for an adjective/noun for someone who is able to speak/ makes speeches very well and uses words effectively to influence/impress people.
A colloquial adjective: silver-tongued. "That silver-tongued con man convinced the entire city that they needed a monorail."
So, to state your goal another way "a public speaker who communicates well and influences hearers".
Additionally, from followup comments, you desire not to imply persuasive toward the sense of having guile - a persuasion with trickery. (Perhaps the worst example of an articulate, influential speaker with guile being a propagandist.)
How about 'winsome orator'? (I don't think winsome alone will do. )
Some may oppose winsome on grounds of its popular definition of... "Charming, often in a childlike or naive way." But childlike fits especially, because it implies innocence and lack of guile.
Furthermore, Among the synonyms for winsome are fair, engaging, amiable. Perhaps I am just picking the synonyms I like.
The American Heritage Dictionary defn. of winsome notes...
"...the Indo-European root *wen-, meaning "to desire, strive for..." ... "... the verb win itself is from this root; its meaning is an extension of the sense "to strive for," namely, "to strive for with success, be victorious." ..."
So a winsome orator describes one who energetically and convincingly communicates.
To some extent, demagogue might also apply.