Amount of 10 Sovereigns from this source: "Chris Given-Wilson, An Illustrated History of Late Medieval England, Manchester University Press, 1996, p.92."
Neat video on the event where they remake the tool with a historical blacksmith: https://www.youtube.com/watch?v=C8Nef1siUus
I hate to ask this, but can you track down Given-Wilson's citation? I ask because sovereigns weren't first minted until the 1480s-90s, I think.
BUT, if Given-Wilson just means pounds (since a sovereign was nominally worth a pound), then I can give some insight. Wool farmer John Lyndewood (father of William Lyndewood, who rose to bishop) left this bequest in his will:
Item. I bequeath to the 30 churches in whose parishes I was wont to buy wool that they may pray for my soul and for the souls of those to whom I am beholden, £10, leaving it to the discretion of my executors to choose the villages. Item. I leave for distribution among poor folk of the country-side, especially in villages where I was wont to buy wool... £10.
Ten pounds is a generous amount.
Based on the UK National Archive's Currency Converter, £10 in 1410 is worth ~£6,300 today. That's an utterly useless number, because spending was entirely different in that sort of economy. But, more useful, is the table they provide below:
In 1410, you could buy one of the following with £10: Horses: 7 Cows: 17 Wool: 55 stones Wheat: 32 quarters Wages: 500 days (skilled tradesman)
First of all, it's worthwhile to know that 55 stone of wool equals 770 pounds (weight) of wool. That's ... a lot.
Second, five-hundred days of a skilled tradesman's wages isn't exactly clear: do they mean working days? Are they spreading these wages out over all 365.25 days of the year? I'm not sure. What I do know is that they're telling us that it's more than the average artisan makes.
Hopefully this will do until a more comprehensive answer emerges.