Sweden has two coat of arms, the lesser who is the three open coronets and the greater has 2 fields with the lesser and has 2 fields for House Bjälbo (a.k.a Folkungar) and uses the current Royal House coat of arms as heart shield.
The motive of three coronets was probebly taken from the city Kölns coat of arms and is documented from being used from at least King Magnus Erikssons time but the first King painted with the three coronets was King Albrekt of Mecklenburg. The three coronets and other Kings coat of arms was painted at the Papale residens Avignon in 1336 when there was a mass meeting there planning a crusade.
There are several theorys about the smaller coat of arms coronets origin. The most belived theory is that they probebly represents the three holy kings who visited Jesus at the stables. In Sweden they are called "Tre vise männen" or the "Three wise men".
Since Norway does not have three coronets in their coat of arms there is the Swedish joke the Jesus was not born in Norway since they have no wise men.
Image of Swedens three coronets coat of arms according to Wikipedia
Image of Swedens greater coat of arms according to Wikipedia
Other three coronots
Denmark also uses three coronets in a field of Denmark coat of arms claiming that the field is is a remnent from the Kalmar Union.
King Arthur has in many storys a coat of arms with three coronets that looks identical to Swedens three coronets.
Motives based on Jesus are not uncommon in coat of arms or in national symbols, for example the flag of Denmark represents Jesus blood.
Cups can also bee interpreted for either Jesus blood or Royal blood (Sangreal or Sang Real).
Denmark coat of arms according to Wikipedia
My coat of arms. Drawing by Davor Zovko
I have written articles for both Svenska Heraldiska Föreningens magazine Vapenbilden and also for Svenska Heraldiska Föreningens homepage.
I have also written som articles in English for use on this site that is not going to be published else where. Some articles are translations and slight modifications of articles I wrote for Svenska Heraldiska Föreningen.