AbdulAlhazred
Legend
By abusive I mean things like re-flavouring your Adamantine sword as being retractable Adamantine claws that can pop out of your hand. The mechanics are obviously exactly the same attack, damage etc but the flavour is very different. And now you get questions like, if everyone else is disarmed then do you get dis "armed" or is it just your luck that you sneak your weapon inside? I could see a lot of DMs freaking out about something like that.
Well, see, with 4e at least, the mechanics are pretty clear. So I would consider this to be a mechanically significant change, and thus a little beyond reflavoring. I mean, you could argue for instance that an ability to hide your sword is on par with many feats, or many magical item properties. It could be a grey area in other games that are less precise, and I'd consider it a fairly minor perk that I might just say "oh, yeah, whatever, OK. You can do that." I mean, it will be useful once or twice, or never maybe, in most games. As a feat it probably wouldn't be considered worth taking by most people.