Function library efficiency

[Yen]

Which of the following cases would be more efficient? I'm pretty sure I know which, but I'd like some input from eithers.
Both cases are clientside.

The first case (a) is to create a class to hold groups of functions, then join it to NPCs that require functions that deal with certain objects.
i.e.

PHP Code:

// Class - mudfunctions
//#CLIENTSIDE
function GetItemPower(itemid) {
  return (@"item-" @ itemid).power;
} 


PHP Code:

// Some other weapon
//#CLIENTSIDE
function onCreated() {
  join("mudfunctions");
  echo(GetItemPower(3324));
} 


The second case (b) is to create a weapon for each group of functions and refer a global variable to itself in the onCreated block.
i.e.

PHP Code:

// Weapon - MUD Library Functions
//#CLIENTSIDE
function onCreated() {
  mud = this;
}

public function GetItemPower(itemid) {
  return (@"item-" @ itemid).power;
} 


PHP Code:

// Some other weapon
//#CLIENTSIDE
function onCreated() {
  echo(mud.GetItemPower(3324));
}