Someone who appears more of an expert than they are [duplicate]

My first thought for this would be charlatan:-

A person who makes elaborate, fraudulent, and often voluble claims to skill or knowledge; a quack or fraud. [American Heritage Dictionary via The Free Dictionary]

Another possibility would be mountebank:-

a boastful unscrupulous pretender [Merriam-Webster]

We can call this person a poseur or poser.

The Wikipedia page provides a fairly good explanation of the term, its use, and its etymology.

Pronouncing it as "poser" sounds hip in a surferish subculture way, while pronouncing it as "poseur" (Frenching it up, so to speak) can sound, ironically enough, affected. But appropriate when someone's showing false pedantry (not a single word, but a useful and relevant phrase), especially about French wine.

A good modifier for various specialists is "armchair". So in this case, we would have an "armchair enologist". Most of the other answers I see here cover the ground of someone trying to pass themselves off as a specialist for some separate purpose. The "armchair" variants, however, rather apply to people making statements with a confidence not proportionate to their actual knowledge.

Most of the answers I see here would apply to a person who would carefully try to evade points of weak knowledge. Not so the armchair specialist: the absence of knowledge allows his theories to flow unencumbered. He is not afraid of blowing his cover.