Here is a my new purchase, An Edward IV angel. I am trying to get a coin from each English king, where possible, and this is my second Edward IV piece. My other piece is a "light" groat. Edward IV introduced the angel during his bifurcated reign, and the reason is interesting.
During Edward's first reign, British silver coins were being smuggled out of England to the European Continent in large numbers. The reason was that they were too heavy relative to Continent coins and were being melted. Edward ended that by reducing the weight of the penny to 12 grains. This reduction flowed to the other silver denominations. I had a bit of panic when I set my Henry VI groat beside my Edward IV piece. The Edward coin was smaller, but then I read the history and realized that I had not purchased "bad coin." Here is my Edward IV groat.

This change would have also required a reduction in the weight of the gold noble to keep things consistent, but Edward had another idea. He increased the value of the Noble from 6s, 8d to 8s, 4d. This didn't sit well with the professional money changers who were accustomed to the noble having the old value. In response Edward introduced the angel which had the value of the old noble. I am sure that I have probably over simplified something here, but that is my understanding.
Here is my new angel, which was issued during Edward IV's second reign (1471-83). The Spink number is 2091.

The obverse shows the arch angel, Michael, slaying or subduing the dragon which represents Satan. It was Michael's job to cast Satan out of heaven and into heck. Today the image of St. George and the dragon that appears on many modern British gold coins represents the same sort of thing.
Edward IV's interest in money was quite consistent with his reign. He was a "business king" who made a fortune in the wool trade, and was very interested in keeping the British monetary system in the best of shape.