I didn't play 4E from very long, but wasn't Longsword on the short list of weapons that had +3 to hit, and thus better than pretty much everything else?
It had +3 prof bonus, yes. Other weapons had the brutal quality, high crit quality, or something else to differentiate them.
Both 3e and 4e did a better job than 5e for differentiating weapons and still making them (reasonably) close to each other in efficiency. I really don't understand why 5e took a step back. :/