The hardest sword users in my opinion are Pit, Marth, and Metaknight, in that order. A good Pit could toy with Wario so bad, especially with his arrows. Strategy for all three is the same, and it'll make fighting them a bit easier. And that is to be more campy. I'm not saying to be full out offense, don't inturpret it that way. I'm just saying lean more on the defensive side than anything else.
Here's a few things to keep in mind when fighting those losers:
Shield Dashing: Simple enough. Shield dashing is when your in your run animation(NOT IN YOUR INITIAL DASH ANIMATION) and you just cancel it with a quick shield. You could fowardsmash or anything right out of this. It's a nice strategy to stop yourself right out of the sword users grab range and wait for them to react. If they attacked they hit your shield, if they grabbed they missed, so follow up with a Dair or Fowardtilt or w/e you want.
Walking: I'm not even kidding. Since dropping shields in this game takes such a little amount of time, and during walk you could do ANYTHING, including shiled, its a nice defense. It's a nice way to keep calm and campy while not being completely stationary. Again, I'm not saying ONLY to walk, thats just stupid. I'm saying to work it in.
FowardSmash out of shield: Duh
Short Hop Air Dodge: If you short hop airdodge right into a sword user you could end up at their backs and set up for a grab or fmash if they whiff a shieldgrab or attack. Wario's shorthopped air dodge is awesome because he could still manuever in the air just the same WHILE in his invincible air dodge state. So take adavantage of that and possibly fake them out if possible.
General Tip: If a Marth player likes to double Fair, just keep in mind that not only are they airdodgeable in between, but they are easy to powershield and could be rolled in between to punish.
Geneal Tip 2: Keep your offense in bursts of surprise attacks.
Hope this helps a lot.
I'm going to update my guide with this, I might as well not waste it lol