Heard of a van that is loaded with weapons,
Packed up and ready to go.
--The Talking Heads, "Life During Wartime"
Just what it sounds like. While no one denies the class of a flaming sword in the hands of an angry Malakite, a good AK-47 with plenty of banana clips can make even the roughest demon cry uncle fast. Since most In Nomine campaigns don't track expenses or money, a character is usually assumed to have whatever mundane gear fits his Role on Earth. A demon with a Role of a cop could reasonably have access to a 9mm handgun and handcuffs, while an angel posing as an author would be likely to have a laptop computer and several notebooks ready to hand but probably no firearms... unless, of course, he lives in a bad part of town. As in most roleplaying games, combat equipment receives special treatment. Armor is rated in terms of the penalty it gives to the attacker's skilll roll (listed as the armor's "Modifier") and in how many hits of damage it soaks up (rated as "Protection"). This can vary widely; heavy clothing gives only a slight modifier and no protection, while steel plating readily "bounces" attacks and can absorb up to three hits of damage. Some armors may be more or less effective against firearms, which may alter either the Modifier or the Protection rating, depending on the details.
Weapons, both ranged and melee, are rated in terms of their Accuracy (which adds or subtracts from the attacker's skill) and Power (which adds to or subtracts from the check digit to determine damage). Much more detail can be found in the Weapons article.
Ordinary stuff, being what it is, is subject to all the indignities of normal life. It can be forgotten, broken, stolen, lost, etc. For something a little more reliable, the careful celestial probably wants an artifact.
A Corporeal Artifact is an otherwise-ordinary piece of equipment that has been "bonded" to the character, either through her own efforts or by the grace of her Superior. The character always has the item on hand when it's needed. Should it be stolen or lost, the character's link to the item can help her find it again -- see the main In Nomine rulebook for details.
These items, also known as talismans, supernaturally enhance one skill for whoever wields it. For example, a gun talisman could give a bonus to Ranged Weapon when it's fired, while a piece of lingerie that's been made into a talisman would probably enhance Seduction. If the character lacks the skill, he still suffers any default penalties, though the talisman's powers may help offset them.
These come in two types. The first, called relics, usually have Songs bound into them. The wielder can invoke them if she has enough Essence, and if she could normally use a Song of that type. A celestial who already knows the Song can't combine the levels -- she has to use either her own ability or the relic's.
Some types of relics are a little more unusual, granting special abilities all their own. The classic example is the Fiery Sword, a mighty weapon that can do celestial damage to a being! Other, stranger types are possible as well ... especially if Eli has been in the area recently.
The second type of celestial artifact, referred to as reliquaries, are simply an Essence battery. Anyone who can generate or store Essence can use a reliquary so long as they maintain physical contact with it. Reliquaires, like living beings, typically regenerate 1 Essence per day until full.
Both ethereal and celestial artifacts have the same bond to their owner that a corporeal artifact does.
For much more on artifacts of all types, including some special Superior-only items, see the Liber Reliquarium by Steve Jackson Games.