When sententious first appeared in English — back in the late Middle Ages — it meant "full of wisdom," but now it usually has a negative sense, meaning heavy handed and self-important.

What is a sententious person?

sententious • \sen-TEN-shus\ • adjective. 1 : given to or abounding in aphoristic expression or excessive moralizing 2 : terse, aphoristic, or moralistic in expression.

What does it mean when a person is pedantic?

Pedantic is an insulting word used to describe someone who annoys others by correcting small errors, caring too much about minor details, or emphasizing their own expertise especially in some narrow or boring subject matter.