Here is a nice description of Yelmalio from the Solar religion materials:
Yelmalio is the Solar deity found where Yelm’s imperial rule does not reach. Associated with the planet Lightfore, his cult brings Light to the darkest frontiers, and he is found among the Lightbringer barbarians and the elves. He is known by many names, including Antirius, Elmal, and Kargzant. However, this book uses Yelmalio, his most common name.
One mistaken assumption is that Yelmalio is the god of pike warfare. He’s not, although the Spear and the Arrow are his weapons. His temples developed a means of fighting in an organised and disciplined manner for their own mundane survival, but that is a historical development, and not something from Yelmalio’s deeds.
So we see Yelmalio where Yelm does not or cannot rule. Yelmalio was present before the Dawn. As Kargzant, he defeated monsters and ensured the survival of the horse tribes. As Antirius, he defended Yelm’s legacy and heralded his return. And as Elmal, he brought Light to the Shadowlands. Now as Yelmalio, he is the God of the Sun Dome Temples, who make sure that Light has its strongholds even in the lands of the Air and Darkness.
One more point – the Yelmalio cult is based around Sun Dome Temples, where the cult is the local ruling cult. It often has “satellite temples” such as in New Pavis, Runegate, or Boldhome, where there are small communities of cult members. Among the communities ruled by the cult, most men initiate into the Yelmalio cult.
Initiates work two weeks per season for the cult, normally doing local militia duties. This is comparable to the six weeks a year Orlanth initiates spend defending their temple – again basically militia work. The main difference is the Sun Dome Temples do militia work in Dark Season, and few Orlanthi communities do.
So remember, most Yelmalio cultists are farmers or herders. Most are militia, not mercenaries.
Do all the worshippers of Yelmalio, whatsoever the way they worshipped him suffer from crippling geases? Few if any of the geases are crippling, any more than the dietary laws of Judaism or Islam are. They set the worshiper apart from the general population, and enable Light to survive among shadow and darkness. And yes, wherever you find Yelmalio, regardless of name, you find a system of geases and gifts.