I'd ascribe the apparent crudeness of design and lettering to it being an "esterling" - an imitation or contemporary counterfeit coin originating from the east of England (i.e. the Low Countries of Europe) that copied the design of English coinage, but was made of slightly less than pure silver. Esterlings plagued the English financial system and were banned from circulating in England, so they are more commonly found in Europe than in England itself. This guy has a whole website about them
These coins, incidentally, are where we get the word "sterling" from, to describe an alloy of 92.5% silver.
As for the question about the "bendy metal": pure or nearly-pure silver is quite bendy enough, when it's as thin as these coins are. Not only were many mediaeval silver coins "bendable", they are often found in a bent condition when dug up. A common method for carrying coins around back then was to bend the coin about a piece of string and carry the string around your neck; when you needed a coin, you just grabbed one and pulled it off the string. Many hoards in Europe are from a lost string, where every single coin is bent around a now-rotten-away piece of string.
Note that while the coins may have been quite "bendy" back when they were made a thousand years ago or thereabouts, they are no longer bendy today. Silver slowly "crystallizes" and becomes more brittle over the centuries, so a coin that a mediaeval person would have been able to bend would just snap if you tried to bend it today. "Unbending" a coin that has been found bent is a skill and art, as it needs to be done very slowly and carefully in order to prevent the coin simply snapping into pieces.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis