Character

Ninja Skills descriptions (Japanese Backgrounds?)
https://jp.finalfantasyxiv.com/lodestone/character/1912534/blog/3375677/

Ninja Skills Description 5.0 Japanese Background
https://jp.finalfantasyxiv.com/lodestone/character/1912534/blog/4120655/

Ninja Skills Description 6.0 Japanese Background
https://jp.finalfantasyxiv.com/lodestone/character/1912534/blog/4865381/

毒盛の術 Dokumori
毒 means "poison" (or "toxin"? "venom"? sorry, I am not familiar with the use of this word."
毒盛 means also "poison"(verb). We Usually say "飯を盛る" when we serve rice, and "話を盛る” when we exaggerate a story. "毒盛" means serving poison... serving?

百雷銃 Kunai's Bane
百 means "hundred",
雷 means "thunder",
銃 means "gun".
百雷 means numerous thunderstorms. Compared to a very loud sound or voice.
Also please refer to https://www.ninja-museum.com/ninja-database/?p=4186
It shows 百雷銃, as "Fireworks similar to firecrackers. They emit a continuous roar."

口寄せの術・蝦蟇仙 Deathfrog Medium
口寄せの術 means... summoning?
蝦蟇 means huge frog, maybe you know it in NARUTO.
仙 means... hermit? "Toad Sage"?

是生滅法 Zesho Meppo
That everything that has life will surely perish and die at some point.
The truth is that all things are not everlasting and immutable, but are born and perish.

天理人道 Tenri Jindo
天理 means the principle of nature. The reason that leads to all things.
人道 means the path that should be followed and performed as a human being.