Trying to steer this thread back on track (futile effort though it may be), using most weapons in different situations is a question of tactics and knowing what to do. Exec Sword has attacks to deal with just about anything, but they’re quite separate from each other and while simple in purpose, need a bit of premeditation to use because of their single-purpose nature.
Its light attacks cleave through a horde; its heavies decimate armor and other single targets; pushing can open up shields. You cannot simply keep swinging to destroy everything; you need to know what you’re doing - and make space and time for those heavies if Elites come with the horde. Effective dodging and pushing can create that space even in the middle of intense combat. Of course, as others said, another trick is to complement your melee with the ranged weapon: if armor, alone or mixed with a horde, seems to be the problem (and if that’s the case, another melee weapon may be a better choice for you as Exec’s single target damage is very good, armor or not), Repeater Handgun or even Blunderbuss can deal with them quickly; if Shieldvermin bring in more problems, aimed Handgun shots ignore the shield and still penetrates armor well. In fact, quickly switching between ranged and melee is a trick that’s quite deeply engraved into higher-level players’ skills, and it’s pretty integral to dealing with a lot of Elites and Special on later difficulties.
So no, I don’t think Executioner’s Sword need changes. It’s strong and can deal with different situations, it just takes more skill and knowledge than many other weapons to use its abilities well.