I have a mate that has a male betta in with quite a few swords and guppies and there are no probs, from what i hear it depends on the betta, some are fine some aren't.
Yes, like Snowman said, bettas personalities differ greatly. For example, my male betta Jerry is a hippy fish, swims slowly and I doubt he'd ever be vicious if I was to put him in a community tank. But there are those bettas who would flare, dart about and tear the other fishes' fins.
Swords look nothing like bettas so there should be no problems (guppies, however, are not reccomended). Having said that. watch your sword isn't too nippy for the betta as some can be. Swords are also usualy large enough (and fast enough) to not be attacked or harmed by a betta.
I wouldn't worry so much about the Betta attacking the Swordies, as the Swordies nipping the Betta. Some of them, especially the males, can be very nippy. Maybe you could consider only females? As they tend to be a lot less nippy, and pretty peaceful too.