I see 3 classes that have Self Sustain issues, Ranger, DK, and Sage.  Using + HP on hit as an argument is invalid due to the fact that some classes get 35 hits on every skill while others get 4, this changes the +10 hp per hit to go in a range from 3,50 to 40 per mob.  You didn't bring it up, I DID.  The OP said there are classes that have very poor self heals, especially in PvE.  I said it was rich that you were saying that HP self sustain is fine when you have a skill on an 8 second cooldown and another that has to hit nothing on a 30 second cool down to say classes with a 30 second cool down ability that heals for less than your 8 second cool down ability.  The fact of the matter is, DK is bad off, and Ranger has even less self heals on the base kit.

Add-ons, maybe?  Awakening Sorc has some really, really bad mana sustain.  So I use mana regen on Violation (spinny helicopter move) for PVE.

This part of this statement isn't accurate. You don't get HP back for every mob you hit. You get HP back once for each time a hit lands. It why skills like Kuno lethal spin can't heal her from near death to full HP when your hitting multiple enemies with it. Example liethal spin hits 20x it heals 50 HP per hit so it heals 1k HP. If you hit one enemy with lethal spin it heals you for 1k HP, if you hit more than 1 enemy with lethal spin it heals you for 1k HP. PA isn't that stupid that they'd allow players to heal from 0 to full using one skill just by hitting more enemies if that was the case you won't need HP pots to grind high end zones and you wouldn't need nearly half the DP either. This why Guardian doesn't regen 1k-2k each time she uses a skill despite having a passive that heals her for 100-200 hp each time she hits something with a skill.

If you think I'm wrong feel free to test it your self go to shultz guard take off some AP and DP and see how much HP you regen with regen skills when hitting one mob or hitting 10 mobs you will find that you don't regen more HP from hitting more mobs.

To a point,
Lethal spin is Hit Damage 969% x 12
Extra Hit Damage 969% x 8 -https://bdocodex.com/us/skill/2148/

The x12 counts as one hit, x8 counts as a second hit. So the 50hp will proc only 2 times, doing the full animation, hitting 10 mobs with both hits, is 500+500hp. So like you said, 1k hp. Getting 1k hp from hitting 1 mob sounds a bit odd to me, I could be wrong, or it could just be a kuno thing.
If it is just a kuno thing, it'd make sense considering ninja's ebuff gives +50%hp -https://bdocodex.com/us/skill/2109/ vs kuno ebuff doesn't give any hp -https://bdocodex.com/us/skill/2150/. Could be their way of 'balancing' your class' survivability compared to her counterpart, ninja.

And Guardian's passive states 'skill' not per hit. https://bdocodex.com/us/skill/5053/

Not valid, everyone has a different hit count as I stated earlier, Violation does 12 Hits, where as most DK skills don't do that many hits and are not spamable.  Violation can be cast repeatedly for no damage reduction thus spamable in combat.  DK doesn't have a single skill that does damage on CD like that.  Ranger is in the same boat, yeah you can put +HP on Waltz of the Wind, but Spaming it is a serious hit in DPS for a minor HP recovery because it's only 6 hits and about 2x as long to do a full animation that Violation does.  

There are different types of hits dude, you have 1000% x 10, there is 1000% x1, max 10 hits.  If it says a number of hits, then hits does use an addon or base ability, however if the skill also says +50 hp on 1 hit vs +50 hp per hit the + hp behaves very differently.  Some skills have 1, 2, 3, .... hits, some skills just have 12 hits, some skills don't have a hit count at all.  Yeah at a glance 2 skills on 2 different classes can look like they do the same healing, but based on how the hit works and how the effect is applied either all hits or only 1st hit, second hit, or even if there isn't a hit count at all will change how those secondary effects work.  There also is this thing called "effect nullified on CD".

I really don't think you understand how all this works and are arguing from a point of ignorance instead of a point of knowledge.

I don't think you rightly understand, and honestly aren't even worth responding to. "Truth does not belong to the one who shouts the loudest."
But here you go.

1000% x 10 = 1hit of 10x damage
1000% x1, max 10 hits = 10hits of 1x damage

'+50 hp on 1 hit' would mean the first hit only, so say the 1000% x 10, even if its had an 'extra' or 'second' hit thats another 500% x 10, it'd only count for the first hit of 1000% x 10. It'd only proc the +50 hp once on the first hit, not 10 times.

'+50 hp per/every hit' would be better on 1000x1, max 10 hits than 1000 x 10, lets take DK's Touch of Exploitation, 923% 3, Max 4 Hits. It'd proc the +50hp 4 times, not 12 times.

"effect nullified on CD" tends to suggest its a spammable skill, aka you can use the skill while it is still cooling down, but it won't apply things like say a CC or +HP.
(editing this to make it easier for you to understand because I know you're kind of special)

Btw, since you're talking about Awakening ranger,
Cold Blade -https://bdocodex.com/us/skill/1878/ 1, 2, 3 Hit Damage 794% x 2, 4 Hit Damage 794% x 4, Maximum 10 targets, 5s cd
HP Recovery +41 per every hit
41hpx10targets =410hp and if it hits 4 times, essentially up to 1,640hp every 5s.

And why would you put it on Waltz of the wind? Dafuq is wrong with you, if anything you'd put it on Blasting gust + Will of the wind. Toss +hp on both blasting gust and will of the wind, then hold A/D+Shift+Q+LMB.

HAHAHAHAHA you suggest COLD BLADE?  HAHAHHAHAHAHAHAHAHAHAH OMFG HOLD ON I NEED A SECOND, HAHAHHAHAHAHAHA YOU ARE AN IDIOT.

No one ever uses cold blade, unprotected short ranged, go to any, and I mean ANY ranger stream and ask them if they can use COLD BLADE to heal.  You might get banned for stupidity from their channel for just asking such a stupid question.

Low low LOW damage, the reason it heals so much in 5 seconds is because it's unprotected AND it takes bout 2.4 seconds to cast all 4 hits.

Lets compare that to purification, the ability basically cancels itself if you blink you miss the animation and you just self healed the entire amount.

Then you suggest not 1 but 2 tier 1 skills for +hp addons to get half of the HP back purification gets in 1 cast.  This and you get to sacrifice all of your other good addons, You now can't stack crit damage, crit rate, attack speed, monster damage, - DP, Move speed, and accuracy.  Because of the long CDs ranger needs to have 2x Monster damage on different skills, 2x attack speed, 2x crit rate, 2x move speed, while being able to have -DP and + Crit damage on a spamable skill, while still utilizing at least 1 T3 skill.  

Clearly you just Theory craft and do not actually look at anything of any class.  You don't understand how incredibly slow it is to cast Cold blade for it's full duration.  Go ahead, make a Trial Character and "SPAM" cold blade just once, then realize that cold blade is unprotected, someone sneezes at you and it cancels making it do zero HP heal, and it has almost no Range nor AOE let alone having shit DPS.  Cold Blade is the only Ranger Awakening ability that is sub 950 then it only does x2, x2, x2, x4 on each hit. Each hit is about .6 seconds, a full Cold Blade Combo is over 2 seconds for under an 8000% or about 3,800% per second.  Compare that to Waltz of the wind, 6,660 % damage every second, and you are not going to spam that you are going to use it as a filler.  Compare that to Breezy Blade 6,440 instant cast animation cancel off Waltz.  Sorry but you cut your DPS by half just by casting Cold Blade once.  Maybe you can tap Cold Blade every 10 seconds if the mobs have high evasion for the accuracy buff, but that is it.

Let me recap really quickly, unlike Valk who has really short spamable CD abilities, Ranger doesn't have the Addon slots to spare on not 1 but 2 Tier 1 abilities.  Most of Valks abilities are on a 5-8 second CD which means that as you spam them your buffs are always running, where as Ranger has a 9-15 second abilities making it neccessary to double up on addons to be as effective while not getting any sustain.

EDIT:

Just did a test on your 1640 HP every 5 seconds, no you don't get that much HP every 5 seconds, I actually had to test it because I never use it due to it being such crap, you get 410 HP that is it.  You get 41 HP for each X on each hit that lands.  So you get 82, 82, 82, 164 on each of the hits The 4th hit being x4 giving 41x4 while the others are 41x2 and it doesn't matter if you hit 1 mob or 500 mobs, it still heals for exactly 410 HP if all 4 of those slow ass hits actually go out.

I really don't think you know what you are talking about when you do anything.  Don't believe me how slow it is and how little it heals for, Create a Trial character Go to the Battle arena, take all the gear off and shift RMB Infinite Master, put the gear back on, you get 1500 HP missing, now try and hit as many targets as you can, in fact get 10 friends, even 3 friends and have them stand still and see if you can heal for more than 410 HP.

Whelp, then there you go, there is a suggestion on how to fix survivability for said classes. Change it to +hp per target rather than per 'X'. Was that so hard to give actual input and suggestions on how to fix shit?