"I think Deathstroke had a lot of possibilities with Arrow but, I think they took it in the wrong direction," Bennett told theMusic.com.au during an interview in support of his appearances at Melbourne's Supanova.
"I think they should have honoured the Marv Wolfman character who was literally unstoppable. I read the DC comic books and thought Deathstroke was so bad arse because they make it that nobody can stop him. He's not even super-powered, he is just a mercenary," explained Bennett, who also starred as a villain in Warner Bros.' The Hobbit films. "It took the Justice League to defeat him; it took an army to take him on. In Arrow, it took a while for Oliver [Queen/Arrow] to prove his point, but [season three] was just a beating of Slade, adding insult to injury."
While there were quite a few similar complaints from fans about Bennett's sole Season Three appearance on the show -- where he was defeated by Oliver and Thea after escaping from his prison on Lian Yu -- the way Deathstroke was handled in the show isn't dissimilar to how major villains are frequently depicted in the comics.
Called "villain decay" on TVTropes, the idea is that since most villains are nigh-invincible in their first appearance so as to make them seem like a legitimate threat to the heroes, subsequent appearances where they're dispatched more easily can discredit them in the long term. See also Batman Begins villain Scarecrow's appearance in The Dark Knight, although that was arguably redeemed by his handling in The Dark Knight Rises.
Arguably the biggest news in the story is that Bennett will not return to Arrow...but that's only stated in the article; the quotes themselves don't support such a bold statement, unless there's more to the interview that will run later.
Of course, Slade Wilson is now rumored to appear -- now played by Joe Manganiello -- in the forthcoming big-screen adaptation of DC Comics' Suicide Squad. After his apprehension last season, many fans wondered whether Deathstroke might be a part of Arrow's Squad when he or the group resurfaced in Season Three. Ironically, it seems likely given what has been said about Deadshot that both Deathstroke and the Squad could be much harder to use on Arrow now that the movie is happening.