As bands go I think Maiden are just about perfect. All the members are excellent on their instruments and the songs are normally about subjects that are much more interesting than those most bands would attempt.
Every so often, though, amongst lyrics that are usually highly literate, there appears a grammatical error that can be jarring for a pedant like me. At least, they seem like errors to me; some of them may just be clumsy or awkward phrasing. Sometimes these happen in songs that I really like, but luckily the music normally prevents it from ruining the whole track.
Consider:
"Torches blazed and sacred chants were praised" ('The Number of the Beast')
"Praised" is a verb that takes a direct object, meaning you can't just say "He praised", you have to say "He praised something". In this case, what is it that is being praised? It appears to be the "sacred chants", which is a very odd thing to say. Clearly I'm being pedantic, but isn't there something a little bit wrong with that sentence?
"Killing on a scale to comprehend" ('Mother of Mercy')
The verb "comprehend" means to understand or to include. Perhaps the meaning that is intended here is "Killing on a scale too huge to comprehend", but that isn't what it says. As it stands, the meaning of the line is a mystery to me.
This next one isn't really a mistake, I don't think, but it's always struck me as a clumsy phrase. Fully expecting to get mildly flamed for this, here it is:
"Hard to stop the surmounting terror" ('Hallowed Be Thy Name')
The usual phrase is "mounting terror". A google search for "surmounting terror" gives results that consist almost entirely of lyrics for 'Hallowed Be Thy Name', and a few links here and there for other things which I wouldn't mind betting have been put together by people who know the song. Essentially, this phrase pretty much only appears in this song. So, marks for originality. It makes sense too, in the sense of terror that overpowers or goes beyond or gets on top of the narrator. It just jars because it sounds so similar to the usual phrase that it sounds like the lyricist has got it wrong. Fair enough if you're James Joyce or some other "safety pun factory", but experimenting with language in that way doesn't seem to be a feature of the rest of the song, so it sounds out of place.
I should say that these are three of my favourite Maiden songs. 'Hallowed Be Thy Name', especially, which does it for me every single time I listen to it. I expect I may be the only person who gets (mildly) bothered by things like this, but like I say, when a band does so many things right, it's easy to forgive small linguistic oddities like these.