Hebrew astronomy calls Jupiter Tzedek, righteousness, and that one fact explains most of the confusion around this angel.
Because the planet is named for justice, every angel attached to it acquires a name built on the same root or a near neighbour of it. The sephirotic table gives Chesed, Jupiter's sphere, to Tzadkiel, the righteousness of God. The grimoire tradition gives Thursday, Jupiter's day, to Sachiel. Zadkiel, Zedekiel and Tzadkiel circulate as variants of the first. The result is a small cloud of similar names occupying the same planetary office in different systems, and reference works differ on how many angels are actually in the cloud.
Sachiel's own credentials are the day scheme. The Heptameron gives him Thursday, dies Iovis, which reaches English as Thursday through the Germanic identification of Jupiter with Thunor, the thunder god. Jeudi and giovedi keep the Latin.
The offices assigned to him are the classical Jupiterian ones: wealth, patronage, law, increase, the favour of superiors. Those are read off the planet's character in the astrological tradition rather than off anything told about the angel, which is the general rule for the planetary set.
Whether Sachiel and Tzadkiel are one angel in two transmissions or two angels in two systems is genuinely unresolved. Some tables merge them; others keep them apart. This collection records both, in their own systems, rather than choosing.