As others have said, everything you get offered gets out-classed later in the game. So don't have FEAR OF MISSING OUT when picking. The question perhaps is more along the lines of what will you being doing that out-classes which items the fastest or slowest.
Magma Shortsword, if you joining the Warrior's Guild (you will not be, but almost all Warriors, and many Clerics, do) then the Magma Shortsword is junk as you can buy it in the Warrior's Guild. But outside of joining the Warrior's Guild, it's quite a while before you can get a better fire melee weapon be it Light, Hand or 2-Handed. For example Sword of Flames is available early if you find a travelling merchant but is 9.2 DPS vs the Magma Shortsword's 11.9 DPS. The damage-equivalent sword is a Deep Cauldron raid, the equivalent Axe is a Wyverntail Complex raid, you get a 2H firestick after/during Web of Terror.
Breastplate of the Forge would be better if, yeah, Lionskin Cuirass wasn't so good and available in the game so early. You get +9 Health and +10 Fire between the two... nice, but hardly worth raving about. It has better chest fire protection that other breastplates until Ashen, but realistically you'll be swapping it out the moment you can get better armoured armour; so the likes of Legion, Jewelled, and other AC4 items over the AC3 of Forge. If you're wanting to build companion Fire resistance on the cheap it's worth thinking about, but I never pick it.
The Ring of Health gives good Toxic resistance (+20), and is Limited, but you can get BUCKETS of Rings of the Frozen Hearts (+18) from the Crimson Hills, and the Greater Ring of Endurance (+30) is dropped by Manticores and in some dungeons.
Arcane Pendant, as other have said, Brother Ladan's Holy Symbol outclasses it; but that's quite a quest in and of itself. (And as is pointed out, it's not necessarily the best pendant out there).
IMO if you want something for you, Arcane Pendant. If you want a Companion bit of kit, Magma Shortsword.