Dead isn't meant to be "shiny", it's meant to look dead, dying, decayed, or similar. A lot of people have said about the outline being to dark, which I'll admit it is, but to change the outline of all of the things with black outlines would take time, time which I unfortunately haven't wanted to spend working on this.
The way I see the Terra Blade, in vanilla, is that it is the blade of the game, hence the name Terra, and when it was made it was the strongest blade, until stronger ones were added. And games need code, hence the idea of the Code items as the alternative. The Terra Blade doesn't even have much in its sprite to signify the night... It's just to bright of colors, for the most part(and overall Terra items are difficult to sprite).
And you have to remember one thing - This is a mod, it doesn't have to fit in exactly how Terraria would do things, instead it can and will rely on its own ideas. I do need to work more on this though, especially the thread... But another thing to remember is that all those sprites were made by one person, and all are planned to be made by that one person. The Dead Edge was the first sprite I made for this mod, and the first sprite I made from not spriting for a good long while, and my later sprites I made are definitely probably better.