Sounds like this spell could be used AFTER a dragon’s frightening presence.  If any party members fail their saves, use this spell, and since the dragon’s description says “if spell ends, creature is immune to fear for 24hrs.”

by that logic, it should only take the concentration to award the Temp HP, right?  As soon as it is cast on PCs, they are no longer frightened, right??  
am I reading these two things properly?? 

Why is this listed as a Oath of Glory spell when Paladins already get Heroism by default.......... <:\

It's listed as both, because all paladins have access, but Glory paladins have it always prepared and not counting, so it is important distinction.

To go to spell itself, I'm surprised with so many positive comments on it. Both in games I dm'ed or played in, the temp hp buffer on one person would be of minimal value - there's always other targets to chase, and if temp hp target doesn't get hit, at best you could think of it as anti-aggro spell, which, depending on party, can be either great or terrible. Immunity to frightened is nice but: a) it's not really a debilitating condition outside of melee characters. Disadvantage on attacks is liveable penalty, and not being able to walk closer to fear object is not desired anyway; b) There are much better spells for it, most notably, Calm Emotions (ranged aoe that targets only friendlies, also mitigates charm, just a circle higher compared to heroism) 

Quote from Argali_Red >>

am i the only one who thinks this spell is bit bad?

granted maybe im focusing too much on the temporary hit point part of this spell, and not the fact that it grants flat out immunity to the frightened condition, but the hit point part really does not scale well at later levels.

that being said, again, immunity to  frightened is actually really good. just wished the temp hit  points scaled every other level.

It is bad. You are using up an action and concentration on the spell, you have to be in touch range to apply it, and it only lasts 1 minute (meaning it can't be used and maintained well before combat). In return you get frightened immunity that lasts only as long as your concentration as well as some temp hp at the start of each turn. Which also means you won’t see any temp hp until the start of your next turn.

The classes that get it are some of the most concentration heavy classes. Bards have better things to use their concentration on. As do clerics and paladins frankly. Overall I think you are correct it's not a good spell. It would be if it took a bonus action to cast but as is you give up too much to cast it.

Probably stupid questions but as I am in my first real campaign I am still learning. 1st, will this cause a downed person to come back to consciousness at the beginning of their turn? 2nd, does the spell casting modifier also include proficiency bonus?

I am trying to gauge whether this or Protect Against Evil & Good are the better option to help protect my party.

1. No. Temp hp is like a buffer to your actual hp and doesn't actually heal you.
2. No. The spell casting modifier does not include you proficiency bonus so ex: if you're a cleric you'd use your wisdom modifier which is generally between 1 and 5.

Protection Against Evil & Good can be useful not only for providing disadvantage from attacks of certain creature types but other uses such as protecting someone from some creatures possession or charm effects as well or make it easier to overcome those effects. It is also listed as one of the few ways to prevent the brain replacement from an intellect devourer, which are dangerous aberrations. I think Protection Against Evil & Good has more utility but they're both still somewhat niche spells that can be useful under the right circumstances.

What spellcasting mod for the guild signet?

To me the temp HP part of the  spell is weak. If, as others have said, the temp HP scaled up, and/or the duration was longer (hours instead of rounds), maybe it would be useful past level 2 or 3.  But at level 5, this is already a waste of a spell slot unless you expect to be going up against something that you know will frighten. 

Quote from Argali_Red >>

am i the only one who thinks this spell is bit bad?

granted maybe im focusing too much on the temporary hit point part of this spell, and not the fact that it grants flat out immunity to the frightened condition, but the hit point part really does not scale well at later levels.

that being said, again, immunity to  frightened is actually really good. just wished the temp hit  points scaled every other level.

 
What is interesting now is that the "Twillight Domain" subclass of Cleric has a version of this which scales incredibly and is in fact full AoE 1d6 + cleric level temp hp at the end of a creature's turn within 30 ft means that even for a single target this channel divinity option outscales heroism by ... lvl 2
And since it IS a channel divinity it doesn't require concentration either. And since it scales with your level, well on lvl 10, 13 temp hp for the entire team every round is still really good.
And you can just warding bond the character whom takes the most damage.

I feel like it was almost "designed" to fall off. Some spells in the lower tier just don't carry over well to mid and high level. Happens with most evocation spells, you wouldn't upcast burning hands to something like 6th or 7th level if you had access to a bigger and more damaging effect. I think they wanted other spells to take the spotlight later on.

Edit: Just thought about this, if you want it to carry over better you could give it an extra 2 or 3 temp hp per level or, stranger idea, make it to where if cast past a certain level, it doesn't require concentration. Maybe 5th or higher so you aren't just getting the benefits essentially for free (also just one target at a time, unless using twinned spell)