True, those redundancies implies a lack of confidence and destroys the argument.
Discussion
This implies you think arguments should stand on the confidence of the arguer. I disagree, I think mostly, arguments should stand by themselves.
That is, only if the discussion at hand is an honest attempt to explore and learn. If it's one about convincing someone, sure, spout your dogma with confidence, it's the only way to convince someone that doesn't think for themself.
Evey discussion should have an honest attempt to explore and learn.
And no one will be convinced as you say, preferably learning, from someone lacking confidence on what they are speaking about. It might be bs what the confident person is speaking about, but that is the duty then, to verify.