Divine Blessings

The deities bestow thier blessings upon the faithful in many ways, though there are generalities that can be found between these bestowments - referred to generally as Blessings.

Effect

Minor Blessing

Little to no obvious effect - usually only conveys that one is in the service or purview of a deity, such as belonging to the clergy of a deity or having the deity as a patron.
 

Lesser Blessing

  Only a minor effect if any - something that would easily fall below the notice of others if not drawn attention to. Usually conveys a deity having a favorable opinion of the individual, family, or organization, but not enough to convey their full favor. Usually some form of crest, birthmark, or other cosmetic affectation.

Blessing

A moderate effect, marking one that carries a deity's favor directly. Usually gives the holder of such a blessing a boost in skills that aid them whatever endevors helped them garner their deity's favor - one blessed of a smithing deity may find they are stronger than others to aid in their craft; while one blessed of a plant diety may find they intuitively know how best to care for them. These skills, while obvious, are usually not so great that they could not been taken as innate affinities. 

Greater Blessing

A major effect, marking one as a champion of a deity. Recipients are granted powers and/or skills beyond mortal ken, related to their deity's domain(s). A rare blessing, as it can give nations advantages over each other should a recipient align with any one.

Side/Secondary Effects

Minor Blessing

Many deities are more prone to respond and answer the prayers of those in their service or under their purview as a patron, but this is by inclination and not an assurance. 

Lesser Blessing

Similar to a minor blessing, but carries more weight.

Blessing

As one who carries a deity's favor directly, those who carry a Blessing do have the ear of the deity that favors them. Their prayers are often answered directly, and their deity is very likely to answer a call for aide or council. 

Greater Blessing

Champions of deities carry so much divine energy that it may give them secondary powers beyond what a diety intended as the recipient masters their control over the strength they have been bestowed.

Manifestation

Minor Blessing

While the deity themselves are unlikely to offer anything, often not choosing the recipient of a minor blessing themselves, those who see themselves as in service to a deity may choose to wear or carry tokens representing their diety. 

Lesser Blessing

Usually, only a cosmetic affectation - an unusual hair or eye color, a spcficially shaped birthmark or crest upon the skin, or similarly mild mark. These things can be faked, any may go unnoticed if the deity who first granted the blessing does not track those who inherite it. 

Blessing

A magical crest that must be called upon to appear, showing the mark of the deity that bestowed it. Alternatively, an artefact that answers only to the will of the blessed mortal it was bestowed on. 

Greater Blessing

Nothing - the skills shown by a recipient of a Greater Blessing are believed to be too obvious to require proof of divine bestowment.

Applied Restriction

While it is possible to carry the blessings of multiple deities, they can only be from deities within the same realm pantheon - that is, one could carry the blessings of two or more demon deities, but not a demon deity and a human one or vice versa. 
This is due to the fact that dieties share metaphyical energy with their realm of origin, each realm being a discrete pocket of reality formed and maintained by the energies of its deities. As such, their energies do not mix well - and would over time deteriorate the soul of a mortal should they attempt to carry the favor of deities of multiple realms.
The only exception would be Minor Blessings - which do not carry enough divine energy to cause such a clash.