The ancient sculptures unlock a sealed door under the Statue of the Seven, which leads to the Silver Stars fallen in the snow.
Underneath the Statue of the Seven at Dragonspine is a path that leads deeper into the mountain, and inside is the first ancient sculpture and a sealed door. Interacting with the sculpture will illuminate a rune on the wall, and from there you will need to find and interact with the other seven ancient sculptures to open the door. Each will look like the one found in this bedroom (and in the screenshot above). Below is a map with each ancient Genshin Impact sculpture pinned (the banner with an exclamation mark).
There is only one ancient sculpture that will cause you grief in Dragonspine and ultimately slow down your journey to acquire the Snow-Tombed Starsilver claymore. Atop Dragonspine sits an ancient sculpture, but you can't get to the top until you interact with three orbs frozen in the permafrost. You'll find the first one pretty easily - it's the object you interact with after using four Scarlet Quartz to melt the permafrost blocking the Frost Tree in the snow covered path. The other two orbs are found similarly, one at the bottom of Starglow Cavern, and one just south of the waypoint in Wyrm's Rest Valley (there is an ancient sculpture marked on the map here) .
Once you have interacted with the 8 ancient sculptures, return to the Statue of the Seven in Dragonspine and make your way to the sealed door. You will find that the switch that was once sealed can be used and it will open the door. Inside you'll find a chest containing a Crimson Agate, but the sword won't be inside. To collect the Star Silver Clay that fell in the snow, you will need to light the four torches in each corner of the room. Once you've done that, a short cutscene will play and the claymore will appear in the center of the room. Interact with him to collect him and add him to your ever-expanding arsenal of weapons in Genshin Impact.
