Couple of things: Any enchantment that is applicable to a weapon is applicable to a monk weapon, so a monk wielding a short sword could use the same poison damage as the rogue in the example. Monks get the extra attack action, so they can make two monk weapon attacks and are still able to use a bonus action for martial arts/flurry if they wanted to; you don't have to make an unarmed attack to be able to use martial arts but the martial arts attacks are always unarmed. Where fighters and the like really take off is using a heavy weapon and great weapon mastery for insane damage gains.
I'm not aware of any +5 weapons in the game, 5e caps at +3 which are very rare.
You are absolutely correct in your assessment of hold person, you are significantly less likely to encounter critters with high wis saves than with high con saves.. con is the worst stat to attack from a player perspective which is a place where Larian can do something to adjust it. As it stands it is pretty broken in that any spell or ability that targets con is at a significant disadvantage overall. A user named Platypusbill at ENWorld forums did a spreadsheet from the MM and it pretty much proves it. And it is a big reason why monks are so MAD, you need a high wis to make the save DC high enough to be worth using. Again you are correct that even though ki comes back on a short rest, it is limited enough that each point counts dramatically, and frankly that is why the Way of the Four Elements is trash, you way overspend ki and really don't net much. One of the big balance issues overall is that ranged spell attack cantrips are way overtuned in 5e, spell casters have insane potential and can still manage decent damage baseline.. particularly eldritch blast and firebolt to a lesser extent.
I'll even go so far as to agree with the idea that monks are undertuned, which is why I'm worried that Larian will break shadow step because it doesn't have a cost and it happens to be one of the only base sub powers that really bring something big to the table (that and quivering palm but that doesn't come till 17). But I think dumping the ki costs on many of the bonus action abilities would go a long ways to making a difference, maybe make flurry of blows automatic but level based similar to the astral monks extra attacks.. ie bonus action for 1 unarmed attack, 2 unarmed attacks at level 11 and 3 unarmed attacks at level 17. No cost for Step of the Wind or Patient Defense, and allow the monk to spend an additional ki point on a stunning strike attack to give the target disadvantage on the save (1 ki base, 2 ki disadvantage). Cut the base cost of everything in way of the four elements by at least 1 ki and make things like fist of unbroken air/water whip baseline no ki with reduced base damage but keep the ki power scaling. So maybe baseline fists of unbroken air does 2d10 + 1d10 per additional ki (save for half) same with water whip or you could even have it do 2d(unarmed dice) +1d(unarmed dice) per ki so that it scales with level. But that is really neither here nor there because WOTC designed it the way they did and never really went back and fixed it.
