An Orlanthi weaponthane has four storms, and Heler is one of Orlanth's four
storms, so four or five (four thanes plus the king) could be good for a
Helering. The four storms seem to correspond to the four magic weapons, but
there are also two hidden winds (above and below) which leads to six (the six
directions/defenders) or seven (those six plus the center/inner direction)
total. I like seven, in three steps: 4, then 2, then 1, representing the
standard supporters, then the special supporters, then the whole which they
support. I can give the same thing a Lightbringer gloss using helper gods (LM,
CA, Issaries and Eurmal), helper specials (Flesh Man and Ginna Jar) and the
leader (Orlanth, again, is #1). A perhaps more GL-ish take on the Lightbringer
division into 4+2+1 is those who seek to restore what others have taken from
them (LM, CA, Issaries, FM), those who seek to undo the damage they have caused
(Orlanth and Eurmal (under protest)), and the unknown/uniting spirit of them all
(GJ). Ernalda has ten servants, and both Umath and Orlanth assigned ten
officers to run the camp, so ten could also be a fair choice, but I prefer
seven.
All the above is generic Orlanthi, however. I don't have a good handle on
specifically Helering or Water-centric holy numbers, which is what I would
recommend you consider: Helerings healing by pouring water on things is an
excellent idea, but doesn't really strike me as a standard Orlanthi
approach. Here's a water idea: use the myth of Engizi washing away Korang the
Slayer with the pure water of his own blood. It's specific to Dragon Pass, but
it does provide a really good source for three being the holy number (the Creek,
the Stream and the River, working together to treat the world-wound chaos has
caused).
Ryan Caveney