I don't know if its intended, but maybe its a Spear thing. The Arena set has also two different types of stats. All listed weapons have STR/CON and the Spear is STR/AGI.
This mob is WAY harder than it should be for conning green. It's a group mob but face rolled a group of 6 with lvl 27 being the lowest. 33 the highest.
I didn't really record it, I've seen him 3x in a row and I've seen him not spawn 12x in a row. The people that I know that camped it got 3 necklaces and 3 belts total, farming for about 5-6 days(normal hours morning to night but not all hours, and not going overnight or anything crazy). If you camped any of the other 3 named, I'd assume it's about the same rarity as the concealment cloak from Gruumsh and either the staff or the nature earring from Krageeli, actually I think the staff dropped the least. Or if you camped the Chief goblin in goblin caves, probably the same rarity as that haste cloak. Just guesses here.
When the chest despawns another chest spawns elsewhere. They don't have individual respawn timers. It seems that there may be a daily limit of chests per area as sometimes the cycle just breaks and no chests will spawn until the cycle resets at 6am (not sure whether the reset happens every day or every x days).
Anyone know what the key is to finding certain ones of these? I feel like they must have some sort of drop system in the game, where certain things drop certain runes more than others. I am Constantly finding Vitality runes from mid-teen-level humanoid mobs (moor'vaki, and lost orcs for example)