From 10 Questions, I have at least 4 questions that received many down votes. I understand down votes if the question asked is not described well, but on this Stack Exchange site, it feels as if there are more down votes more often than I am used to. Is there a reason for all of the down votes?
Typically, we like to see that you performed some sort of research before asking a question. If you hover over the down vote arrow on a post, it states:
This question does not show any research effort; it is unclear or not useful
I only see one question on your profile that is down voted (I assume you've deleted the other ones), and it is about the game Terraria. Historically, this game receives a lot of questions that end up being down voted, primarily due to the lack of research on the authors part.
In your questions case, the research you could have done was simply look up the Muramasa sword. Terraria has one of the most documented game wiki sites out there. Looking at the page for the Muramasa, you could probably gather an answer to your question. The page may not deliberately give you a direct answer to your question, but if you searched through some of the links on the Muramasa page, you could have come to a conclusion on your own. The person who answered your question and you accepted cited the Wiki in their answer as well.
I know it may seem odd that we expect you to do some sort of research prior to asking a question on the site, but it helps to prevent lower quality questions from plaguing the website and duplicate questions from being asked/answered. Our How do I ask a Good Question help page states:
Have you thoroughly searched for an answer before asking your question? Sharing your research helps everyone. Tell us what you found and why it didn’t meet your needs. This demonstrates that you’ve taken the time to try to help yourself, it saves us from reiterating obvious answers, and above all, it helps you get a more specific and relevant answer!
So, in some cases (and likely a lot of cases), when a valid question is asked and it is down voted, it is because little to no research effort was taken prior to the question being asked. Also keep in mind that people are entitled to their vote, and may have any number of reasons why they down voted your post.