There's nothing wrong with "goth metal." More over to imply that only goths have dirges and laments is fallacious at best; go listen to My Dying Bride or most any doom metal band or depressive black metal (don't really recommend that latter, black metal is hit-and-miss with a large miss-to-hit ratio). Doubly more over, "goth metal" isn't a genre.
I really don't like the Disciple of Metal class and I never have. Mostly because it's a huge stereotype and mockery of the "typical" metalhead and metal band. And slo because it uses Dragonforce, Pantera, Dimmu and Cradle of Filth as inspiration (bands that have done more harm than good, except Dimmu, they just annoy me). Not to mention Disturbed and Godsmack aren't actually metal at all....[rantrantrantrantrantrantrantrantrant]
Alright, sorry about that. Just sometimes get out of hand.
Dirgesinger is a good class for debuffers. Though, I've found that the feat Doomspeak replaces it. Unless you really want that undead minion, go with the Doomspeak feat. Though it looks like DoM gets a similar ability. Just stick with DoM and take Doomspeak. Done and done.
Tome of Battle is great for anything. It's manuever system allows you to splash on one or two levels and have those levels scale unlike with other systems (magic, psionics, the various variant magic systems [except incarnum]). Crusader + Bard + Song of the White Raven. And I know how it is to not understand it. But one night, get your hands on it and sit by the fire with a cup of hot cocoa and read through it. Soon, you two will be gossiping about that hot girl down the street like you were old buddies. Trust me. It happened to me.
A warrior bard is always fun (plus suits what you're already doing kinda): Look at Complete Adventurer, around page 105 (I think), there's a feat called Devoted Performer. Now find a copy of Unearthed Arcana and find the variant paladins (since I'm running on the assumption you're evil). Go LE Bard 4/Monk 1/Paladin 15. Feats: Ascetic Knight, Devoted Performer, Ascetic Mage. Then if you can find a way to divorce the Initiate of Milil feat from it's namesake's alignment, grab that up as well. Alternatively, don't take Ascetic Mage and wear armor/take the Dragon Husk option from Dragon Magic/Races of the Dragon/Draconomic. Be sure to use a Monk's Belt or take Superior Unarmed Strike. Pummel stuffs with fists and weapons. =D If you go this route, be sure to get your fists enhanced.
Equipment:
Get that greataxe fixed. Keen is a horrible enhancement. Waste of a +1. Get the wizard to cast Keen Edge on it. INSTEAD, get it harmonized. If you must keep keen, at least convince the DM that improved critical or something will stack with it.
As for keeping with the "metal" theme, you don't need a class to do that. How do you stay metal? You don't give in to anyone; you maintain your beliefs even in the face of adversity; you do not, under any circumstance, let someone else control your life. To be metal you need to be yourself, not what anyone expects of you. Metal isn't killing dragons or being a barbarian or sexing up a princess. Look at all the lame people that do those things, they aren't metal. But the guy who went against the grain and put a picture of a student burning the American flag on the front of his school newspaper, he is metal. Martin Luther King Jr. when he stood up and said No, we're not gonna take this abuse anymore. He is metal. Anyone that has ever stood up for anything even when the deck was stacked against him, they are metal. Yes, even the bad guys who stood up from their beliefs are metal.
Question your character. Is he doing this because he wants to, because he has an unwavering devotion to a cause or belief that has lead him here? Or is he doing it because the fighter threatened to stick that greataxe up his butt if he didn't come along and sing songs?
Being metal is a less an aspect of mechanics and more of roleplaying. Put together a good build and couple it with good roleplaying.