The Mishna (43b) describes a number of differences between the way the ketoret was prepared by the kohen gadol on Yom Kippur and the way it was done on a regular day. For example, every day the coals needed for burning the ketoret would be picked up with a silver mahtah (shovel) and then transferred to a golden one, while on Yom Kippur a golden mahtah was used to pick up the coals and that same shovel was used to carry the ketoret into the kodesh ha-kodashim.
The mishna states: On every other day, a priest would scoop up the coals with a coal pan made of silver and pour the coals from there into a coal pan of gold. The Gemara asks: What is the reason the gold pan was not used to scoop the coals? The Gemara answers: Because the Torah spared the money of the Jewish people. Since the pan is worn away with use, it is preferable to use a less expensive silver pan.
The mishna continues: But on this day, on Yom Kippur, the High Priest scoops up with a coal pan of gold, and with that coal pan, he would bring the coals into the Holy of Holies. The Gemara asks: What is the reason that on Yom Kippur only one pan is used? Due to the weakness of the High Priest. He has to perform the entire service by himself while fasting; using only one pan minimizes his exertion.
Our Gemara also quotes a baraita that mentions a difference between the daily ketoret and that of Yom Kippur that is not mentioned in the Mishna. Ben ha-Segan points out that only the ketoret of the Yom Kippur service had a niashtik.
The source for the term niashtik is unclear. Some suggest that its source is Persian, while others identify it as being borrowed from the Latin Nasticiun. According to the vast majority of the commentaries, it is a covering of some sort. The Tosafot Yeshanim say it was a cover for the handle of the mahtah. This was necessary on Yom Kippur because the hot coals remained in the shovel for a fairly long time, and this made the handle of the mahtah difficult to hold. The explanation presented by the Ge’onim – which also appears to be the explanation given by the Jerusalem Talmud – is that it was a cover for the shovel itself, whose purpose was to keep the coals burning by protecting them.
Rashi understands the word otherwise and argues that the niashtik were two rings that were placed on the mahtah so that they would make noise as the mahtah was carried. The Me’iri suggests that it was a type of flat bottom that was added to the mahtah, allowing it to be easily placed on the ground.