Masonry (Skill) is a very helpful and useful Skill. You use it to create all the Stone and Sandstone Structures (ie. Stone Hut, Sandstone Hall, Shop, ect.) Small Stones, Piles of Sand, Boulders, Cut Stone(Both of these can be found spawning naturally, but need to be mined with a pickaxe), and Sandstone (crafting with sandstone may require a bigger level). These can then be used to create Boulder, Cut Stone, and sandstone which can be used in many structures and items, such as a Sandstone Hall, Sandstone Hut, Medieval House etc. Masonry is a key skill for medieval tribes, such as the last picture shown. It can be used by the greatest warriors of the game too.
The necessities of becoming a warrior is first a Forge. Then you could advance to a Smeltery if you want.