Incense

Psychopomps, as a rule, take people before what could strictly be considered their time- often only by a few seconds or minutes, but before natural death nonetheless. However, they err heavily on the side that favors them- death. As a result, many die in potentially recoverable situations- most typically with regards to wounds, starvation, dehydration, and disease.

Trivia: For a span of several decades, there was a rather large region in which a slit throat would kill near-instantly.
There exist several incenses which, through various mechanisms, will allow one those within their radii to come closer to passing naturally. They're used in traditional medicine as a result. Long after the reign of psychopomps ended, the traditions remained, though then more placebo than anything.
Mechanisms include:

Occluding the area from psychopomp view

Less effective if the relevant reaper has a very small jurisdiction and can easily notice occlusion; more so if the occluded area would only be a tiny blip. Not useful long-term, as it can't block direct manifestation; only passive awareness. Generally used when carting wounded to treatment facilities; the smell has long become associated with ambulances (A/N: no, not motorized).

Distasteful to psychopomps

Causing a sense of discomfort and/or disgust to psychopomps- not even remotely debilitating, but enough to put them off their appetite. Pushes the psychopomp towards doing their jobs to the letter, as opposed to sneaking extra bites. This is the incense most commonly associated with healing.

Cultural Context

While people in the period worshiped psychopomps, they were distant things- for most of the period, even to the greatest warlords and generals, the most one may get from a psychopomp was a single passing conversation on the eve of a great battle. The use of incense developed without true knowledge of its effects.
For example, occlusion incense was thought to improve vitality in small doses, but detrimental to health with overexposure. That's technically correct, but misattributes its effects to be on the body, rather than on surrounding spirits.