I'm sorry but your impudence must be smitten.
Weak? I'm sorry but saying that a character in Fire Emblem is weak is a personal preference and is based entirely on your skill to level up and train a character. Marth is one of my best characters in Fire Emblem 3 currently I'm sorry but he is by no means weak.
Lackluster? His character is lackluster? It's about as lackluster is Link's mirror shield! Just because SNES had trouble with cutscenes and telling stories doesn't mean his character is nothing. There are many many more resources which dive deeper into Marth's character such as the Manga and anime series.
Marth's popularity did NOT come from SSBM alone in the America's without a doubt yes. But Marth was already a #1 FE character in Japan since FE3 was released.
These silly arguments that say "Marth being the first Fire Emblem lord isn't a good reason to include him." Why was he then included in Smash Bros Melee? It wasn't just because of his stunning good looks. It's because Marth's game (being the first Fire Emblem Lord) opened up an entire new gaming Genre (turned based RPGs) and that his third game FE3 remains the best selling game of the FE series.
Sigrud though he may be Sakurai's favourite LORD (emphasis on lord, because Sakurai's favourite FE character OF ALL TIME is Navarre from FE3) but that means nothing compared to the general popularity opinion of Japan, his main audience.
I do agree with you that he is a completely original character in Melee and has no reason to be removed, however saying that Sigrud deserves the spot more than he is like saying Luigi replaces Mario.
Not only that but Sigrud is a COMPLETE copy of Marth down to the last detail of his sword (which it's design is almost IDENTICLE to that of the falchion) Since Sigurd is Sakurai's favourite FE lord, he takes a place in his memories as Ike's alternative.
I'm sorry but anyone who ties to downgrade Marth (let alone someone with the guts to attempt to bring down one of Zevox's posts) will be dealt with accordingly...
Ok, first of all, Marth is not weak because of my personal experience, he is because he has poor growths, and doesn't promote. And he doesn't always have Falchion either.
As a character, Marth is uninspired. He's just the typical "Don't worry, I'll save the world" type of character, with Royal etiquette. He's just your general "Hero" archetype, and doesn't have a very compelling personality.
You want to know why he was the most popular lord as of FE3? Because the only other 2 lords were Alm and Celica, who were nothing special at all. FE4 is widely considered the best FE ever made (for good reason), and Sigurd is a far more powerful, and more likable character than Marth.
I'm not trying to downgrade Marth here, He's one of my mains in SSBM. I'm just not a fan of him in FE, and I'm not the only one. When considering the popularity of a character, you have to take into consideration not only the people that love the character, but also those who hate it. Marth is loved by a lot of fanboys, but he's equally hated by many hardcore FE players. Rarely do you find someone who is on the fence. Sigurd may not be loved by as many people, but he's certainly not hated by as many either. It's like comparing those olds boy bands (like N'sync and whatnot) to Tool. N'Sync certainly had more fans, but they also have many people who hated them, whereas Tool is either loved, or generally liked by a good portion of listeners.
None of that matters now though, beause Marth was already in FE (I could go on about why I think he was chosen instead of Sigurd, but I won't bother) and already is a completed character who just needs some tweaking, and he's ready for Brawl. There is no reason to remove him whatsoever. I don't want him removed. That's the bottom line.