theatreofcomets says:
Meht has Heal ... use on the wounded guards.
Pursuant to all rest of this, healing takes time
"When you rest and consume a ration/waterskin/wineskin, you may re-roll your HP." so that HP mechanic might not be immediately relevant.
The guards, being NPCs, do not have --nor roll-- HP, so the rules are very open when applied to them.
theatreofcomets says:
... skills, while always succeeding to some degree, still need a roll ...
Yes, the Skills change the bottom end of the dice curve, so, by RAW, they apply to rolls. But they also define the characters, and provide fictional positioning.
The fact that
Meht has the Heal Skill justifies him taking actions related to first aid, triage, or even dealing with the dead. Without it people may look askance at such actions.
With the withdrawal of
Leesha's player we can assume --for now-- that there is further NPC healing available off-screen in the general cases where you don't want to take on that ongoing responsibility. Play out as much as you want, but try to keep any references to sidelined PCs to a minimum in terms of impact on said PC.
theatreofcomets says:
... do they also need a properly-justified modifier, or just a flat 2d6?
This depends on the fiction. Show us what you are doing, bearing in mind that 'healing' or full recovery will take time.
If you want
Meht to start helping the wounded, then do that, it might require a roll to determine how successful you are, or the fact that you are a Heal(er) might be all we need, depending on the intended outcome. Show us the fiction.