I have come to the realisation that Bowser is actually a genius. He's been wearing those leather with studded bracelets and collars for years, but it wasn't until I saw the movie Beowulf that I came to realise Bowser's genius.
To slay a dragon that breathes fire, you must rip it's heart out (this particular dragon had it's heart in it's throat, literally). The dragon that Beowulf was tying to slay had a weak point in it's neck, and during the fight, Beowulf reached through that weak point to grab the heart, subsequentially killing the dragon.
Bowser wears those leather studded things to keep the Mario Bros from getting to his weakest points: ankles, wrists and neck. If Harry Potter had known about this, his arm wouldn't have become poisened during the fight with the basilisk.. but a basilisk isn't a full grown dragon anyway (not a dragon at all, I believe).