majesta

No suffix, and the false one is one of the most productive in the language. -estr- is real and busy: lernejestro a headteacher, ŝipestro a ship's master, urbestro a mayor. So the eye reaches into majesta and pulls out maj- plus something like -est-, which feels almost right given what the word means. It is not right. The affix is -estr- with an r, there is no bare -est- suffix, and there is no root maj- for it to attach to. Majest- is a single borrowed unit from Latin.

The joke, if you want one, is that the real Esperanto word for a mayor - urbestro - genuinely is built with -estr-, and its English translation genuinely does share a Latin root with majesta. The seam is false in Esperanto and true in Latin, which is a good demonstration of why you decompose the language you are actually reading.

Choosing between the big adjectives. Grandioza is imposing by sheer scale. Belega is gorgeous, beauty turned up. Solena is ceremonious and grave. Nobla is high-minded, about character rather than appearance. Majesta is the one that carries authority in its bearing: mountains, cathedrals, old trees, kings and anything that makes you stand a little straighter. Majesto as a noun is majesty, and Via Majesto is how you address one.