Welcome aboard. There is still a lot of work that needs to be done. Launch within a year seems too optimistic to me. But since you are now backers, you will at least be able to kill some folks during beta testing during the next year.
Aside from what everybody else said, that sword was designed by a backer as part of a contest and CSE is adding it in game as the reward for the contest. They picked it not because they thought it was historically accurate but because it looked cool and was well done.
But yeah CU is not set on historical earth and the Vikings in CU are not historical Vikings. So CSE is perfectly within their rights to use their imagination and do things for the Viking realm that don't strictly follow history.
It's actually Beta 1 that is projected to start July 4 not Open Beta. There will be 4 beta stages: Beta 1, Beta 2, Beta 3, and Open Beta. Open Beta is likely to start a year or more after Beta 1 begins.