Giltonio_Santos
Hero
Do enemies "know" who has more hit points?
No, but other tanking classes have actual abilities that punish enemies for choosing to attack someone else. I'd say this is the basic principle of tanking: if you cannot punish enemies for attacking someone else, then you're not tanking, you just have high chances of surviving.
Is being struck with a hexed greatsword twice not good damage?
Irda's build uses a longsword, which is a fine weapon for a tank build (which, as I've stated before, has other ways to force enemies to choose it as a target). If it chooses to drop the shield in favor of a greatsword, then it's just another damage build, one that is strictly inferior to the battlemaster fighter (in melee) and the eldritch blast warlock. It's just as good as the str-based champion high elf (I mean, good enough to play, worse than your typical non-maximized character choice).
Are we sure this is the nova round for the fighter? If not, I don't know that the target would be avoided and or disregarded.
All fighter tanks have easily available options to force opponents to attack them or suffer, this warlock has none. In fact, it would have to trust other characters to not deal more damage than it does (not a lot of hope, since even Irda's build could be doing more damage by eldritch blasting), or to manage to stay out of range from their opponents. When we arrive at a point where you need goodwill from the other players to make your build work, "good" is not exactly how I would describe it.
Additionally, do the squishy targets do more or less than this character? And that is disregarding spell use or other abilities on he part of the warlock
They do more. For starts, one hex cast and bladelock is already 50% into its spell slots. The list of damage dealers doing more than that at 5th level encompasses almost all character options that actually care about dealing damage (also, good luck concentrating on that hex, if you end up being hit). You can cast darkness to get more reliable attacks and avoid opponents, but then it's no armor of agathys for you, and you're also making your fellow adventurers less effective, unless you're in an all-warlock party.
That's the weirdest thing about the bladelock: it's also a "mana-hungry" build, and most people speak about its advantages without taking into account that it will spend the most relevant half of its career casting two spells per encounter (if the DM is nice enough to allow short rests after every encounter...). If you're relying on hex and agathys to make you a decent combatant, it means you're not casting anything else until 11th level.
While you struggle, fellow wizard cycles through magic missiles, scorching rays and fireballs, and still has 2d10 fire damage to boot, if anything else fails. If I was an evil monster, you'd have to show me more than hit points in order to make me pick you instead of that friend.