From LSWiki

The Chosen of Vashanka, the God of War

Molin asks, <| So, you believe yourself worthy to join the Chosen of Vashanka? |> 
Molin looks you over.
Molin says, <| Well, I am not sure you are fit, but if you have enough money, perhaps.  An initiation tithe of fifteen thousand gold should suffice. |> 
Molin says, <| But he does not allow any of his flock to wield ordinary, unenchanted weapons, or weapons which do not pierce or cut. |> 
Molin says, <| You can leave at any time, but none of the gods of Sanctuary will accept you after that. |> 
Molin exclaims, <| You may worship here and become one of the Chosen of Vashanka! |> 
Molin exclaims, <| Vashanka treats his worshippers well! |> 
Molin says, <| Welcome to the Temple of Vashanka the Storm God. |> 

Vashanka grants each of his worshippers an amulet as a token of
their devotion and strength, through which his worshippers may call upon
his favor according to their stature.  Those who wear the amulet also
gain resistance to some forms of attack.

Vashanka is always seen in magical black and red armour, wielding
very formidable swords in either hand, exuding strength and power.  Vashanka
is known to be the eldest brother amongst the gods of Sanctuary.  He
considers both of his brothers cowards, and discourages association with
their followers.

Joining

In order to join the Chosen of Vashanka you must have at least a 70 Strength, a Willpower specialty free to invest in courage, and 15000 gold as an initiation fee. While the help file mentions being able to call upon Vashanka's favor, that may apply only to ELF members - no particular commands have been discovered, at least by this submitter.

Abilities

The favor of Vashanka seems to come primarily in the form of a bonus to Strength, Constitution, and Dexterity as well as some minor resistances while the amulet is worn.

Bonuses start at +4 with (0 rating in courage) and can improve, but it's not clear how to increase the effect of the resistances/boosts. Possibly by raising courage? More likely by good sacrifices to Vashanka or simply levels.

Items can be sacrificed to Vashanka on the altar in his temple. The command is 'sacrifice (item)' He will accept any weapon, but as yet no benefit has be found from doing this. Volume is not a deciding factor. Will have to be tested with magical weapons. Only one weapon can be sacrificed at a time.

You place the Sceptre of the Rockfist on the altar.
You feel a sense of a powerful presence.
The Sceptre of the Rockfist disappears.

All of the artifact weapons I have sacrificed have given the same message as above, with no obvious effect.

Specialty Bonuses

Armour Adaptation +1
Armour Lore       +1
Axe               +1
Brawling          +1
Carousing         +1
Combat Reflexes   +1
Courage           +3
Dagger            +1
Demolition        +1
Dirty Fighting    +1
Discipline        +1
Dodge             +1
Find Weakness     +1
Hardiness         +1
Impact Absorption +1
Intimidation      +1
Killer Instinct   +1
Lack of Weakness  +1
Massive Blow      +1
Mounted Combat    +1
Pain Tolerance    +1
Pole Arm          +1
Practice          +1
Precision Strike  +1
Recuperation      +1
Resilience        +1
Shield            +1
Spear             +1
Stamina           +1
Steadiness        +1
Strategy          +1
Subordination     +1
Sword             +1
Tactics           +1
Tenacity          +1
Training          +1
Unarmed Combat    +1
Weapon Lore       +1

Molin says, <| The worship of Athena does not allow the veneration of Ares, so you cannot join the Chosen of Vashanka. |> to you.

Molin says, <| You specialize in scholarship, which is forbidden to Chosens of Vashanka. |>