Bearded axes most likely appeared in Northern Europe, where they were known from 7th-8th centuries. The hook or "beard", i.e. the lower portion of the axe bit that extends the cutting edge below the width of the butt, provides a wide cutting surface while keeping the overall mass of the axe low. This design allows the user to grip the haft directly behind the head when planing or shaving wood. The "beard" of the axe would also have been useful in battle, for example, to pull a weapon or shield out of a defender's grasp. The beard is also used to climb over the enemy's stockade by both Þrándr in the Eyrbyggja saga and Þórir in the Gull-Þóris saga. In addition to the downward-pulled blade, beared axes were distinguished by a straight upper edge.
Soon they reachув to Central and then Eastern Europe, where they became widespread. Through Scandinavian mercenaries serving in the Varangian Guard, the design entered the Byzantine Empire. After the Ottoman conquest of Constantinople, the Sultan's guard adopted axes of a similar design to underline its continuity with the Byzantine Empire. In the 15th century, these axes evolved into one-handed bearded axes with a hammerhead. Through Ottoman influence, these axes spread to Poland and Hungary, where they became known as "czekan."

Old Norse skeggøx from skegg 'beard', øx "axe", German Bartaxt.

Axe of iron from Swedish Iron Age, found at Gotland, Sweden (Wikimeadia Commons, public domain). Source Nordisk familjebok (1910), vol.13, Till art. Järnåldern. II https://runeberg.org/nfbm/0251.html

Russian bearded axe. 10-13 centuries. Modern reconstruction by Maxim Baranov, 2011 (Wikimedia Commons, Vladimir Lobachev, Creative Commons CC0 1.0)

Two types of Scandinavian battle axes. Breiðöx (left) and Skeggöx (Wikimedia Commons, public domain). Source Oluf Rygh: Norske Oldsager (1885).

Compare Sumerian tun₃ /tun/ 'axe' and 'lip; chin; fringe' ePSD2

https://oracc.museum.upenn.edu/epsd2/sux/o0040650

https://oracc.museum.upenn.edu/epsd2/sux/o0040656

https://en.wiktionary.org/wiki/%F0%92%82%85#Sumerian