Warning: contains spoilers for Daredevil #1!
Matt Murdock's new Daredevil costume shows that however his new tenure as the leader of the Hand may go, he's already sacrificed his place as a true Marvel hero. While fans have only seen the mask of Daredevil's new look so far, it includes a detail that has long been consistent with Matt Murdock turning to the dark side.
Recently, Matt Murdock's longtime ally Elektra returned to his life, asking him to help her end the threat of ninja death cult the Hand. Elekta wanted to form a ceremonial group called the Fist to stand against them, but Daredevil initially wasn't interested, accusing her of using the Hand to justify her own ruthless agenda. Unfortunately, the last few months have seen Matt's life fall apart, as his time in jail was followed by the murder of his twin brother, which prompted him to fake his own death and commit fully to the Fist.
Daredevil #1 - by Chip Zdarsky, Rafael De Latorre, and Marco Checchetto - sees Matt in command of the Fist and preaching a new gospel of "righteous violence." It's clear that Daredevil is less in touch with his humanity than ever as he justifies his choices to an unseen interrogator. At the end of the issue, the Man Without Fear finally moves forward into the light, revealing a new look. Matt is sporting a lustrous beard, a new outfit with an open collar, and a new mask which - while similar to his usual costume - has more vicious, curving horns than he sported back in New York. While this change is subtle, it matches a significant history of Matt's horns being a window into his soul.
Generally, the closer Daredevil strays towards darkness, the more pronounced his horns become. This can be seen in several of his costumes - including the alternate reality where he betrayed Doctor Strange and joined the Hand - but was most prominent during the Shadowland event, when he was possessed by the Hand's dark god, the Beast. As the Beast seduced Matt with promises of justified violence, his horns subtly extended, showing how far he was straying from his former principles. Now, as leader of the Fist, his cruel new horns hint that while he may feel he's doing the right thing, he is once again being corrupted by the Hand - this time, in how far he's willing to go to end them for good.
Matt's faith in god and the law have been shaken by his experiences with the justice system and the murder of his brother, and now he's abandoned his civilian identity to become Daredevil full-time. But while he may still intend to do good, Matt has entered a compromising new world where the label of 'hero' no longer applies. As he raises up an army to face one of the darkest forces in the Marvel Universe, Matt is staring into the abyss, and his new mask as Daredevil shows that whatever he might intend, he's not immune to its influence.