Kladenets (Russian: меч-кладенец); also called samosek or samosyok (самосёк) the "self-swinging sword," is a fabulous magic sword in some Old Russian fairy tales. In English translations of Russian byliny and folklore, it may be rendered variously as "sword of steel," etc.
The Sword Kladenets is most famously wielded by Ivan Tsarevich.
The word "kladenets" can putatively be linked to the Slavic word klad (клад) "treasure, hoard," although "a number of philologists doubt" that this word-stem figures in the derivation of "[this] Russian epithet of this sword."
George Vernadsky renders kladenets as "the hidden sword," which concurs with the common motif in the stories in which "this sword is usually represented as hidden under a rock, or under a sacred tree" to be discovered by the hero, such as the bogatyr. Although Vernadsky fails to elaborate, an alternative etymology connects the term kladenets to klast (класть) "to lay or put," and his rendering lies in this camp.
One rational explanation derives the word from uklad[ny] (укладъ, укладный) "steel", hence kladenets is defined as meaning "made of steel" in the Dictionary of Archaic and Obscure Words published by the Russian Academy of Sciences.
Another explanation, credited to Alexander Veselovsky theorizes that kladenets may have originated as a corrupted pronunciation of "kgl'adencyja" (кгляденция) or "kgl'arencyja" (кгляренция), the good sword of Bova Korolevich. The Old Russian tale of Bova was adapted from the medieval Italian romance of Buovo d'Antona, in which the original sword name is Chiarenza. This etymology has been endorsed by Max Vasmer's dictionary, under the entry that defines kladenets as a "magic sword in Russian tales".
Kladenets means "well" (for water) in the related Slavic language Bulgarian (Bulgarian: кладенец), potentially evocative of torrents of blood.