Yes, the goose hunters who found the sword should be rewarded for their efforts. While they may not have been looking for an ancient artifact on their hunt, it is impossible to know if it ever would have been found without them. A museum will make a great deal of money on displaying the sword, so it is only right that the hunters get paid.
Yes, the Icelandic goose hunters that found a 1,000 year old sword should be rewarded in some way. They discovered a cultural artifact and turned t over to the proper agencies when they were contacted about it. It is a major find and they should at least be recognized for their part in the discovery of an artifact as well as a potential archelogical site if any other artifacts are found in the same area.
People who locate antiquities have a choice of whether to keep it for themselves, sell it on the black market, or alert officials so they can take control and preserve them. People who do the right thing should be rewarded not just for their deeds, but as a message to others to follow suit.
The goose hunters should not be monetarily rewarded for turning over the Viking sword because the virtue of their good deed should be its own reward. They found a treasure that is meaningful to their nation's past and their people, and the reward is the fact that the sword helps everyone learn more about their history and culture.