Compare two modern day students of aikido and kenjitsu. Both with similar study habits and teachers. Yes, I totally feel that an aikidoka would (or I'll say should)stand on even ground with the swordsman in terms of ability. 50 years ago, would one of O'sensei's students fair as well, yes. I know Tohei sensei for one would be more than capable. But compare a swordsman from 50 years ago with an aikidoka of today, no, I seriously doubt the aikidoka would fair well at all. It's a total difference in training mentality and method.
I think I'm reading this in a way you didn't mean. The reason people use weapons is that it gives them an advantage. The Japanese used the sword, bow, or musket and arquebus because it gave them an advantage. Otherwise, they would have charged bare handed and slaughtered all before them with their great skill as the Boxer's did in China. Or did it not go that way?
I, for instance, want no part of someone as well trained with a knife as I am with Aikido. Actually, I want no part of anyone with a knife, gun or whatever weapon, trained or otherwise, the percentages are just flat out against you.
Now if you want to compare us with the hand to hand arts that's something of a different matter.