"In old school games, magic item creation was virtually impossible. This made magic items rare to an extreme, and created situations where a single + 1 sword was a huge treasure... magic items should be very scarce in Swords & Wizardry games. The power level of both characters and monsters is quite low compared to other versions of the game." - +Bill Webb , Hall of Bones - A note about Magic Items and Magic Item Creation.
When I was deconstructing Swords & Wizardry White Box to its bare bones to rebuilt it as the lean four pages soon to be known as Swords & Wizardry Light, my main desire was to present a ruleset that could be easily comprehended on a quick read through. That meant not only keeping it simple but leaving out "stuff" that was not immediately needed.
If magic items are rare, then a magic item shopping list is not only not needed for levels 1 through 3, it's probably detrimental to gameplay. Magic items should be introduced via adventures. They should be unique, even if they share abilities in common. Sure, all + 1 swords do plus 1 to hit and to damage, but one glows with a dull blue light when wielded and was used by Gragnut The Damned, the Orcish Chieftain who fought the party to the death. Another glows a bright yellow when wielded and was found in a treasure hoard guarded by Ztzaaath the Wyvern. The party still talks of the encounter and the piles of silver they carried away.
Not including magic items also saved space (and limiting yourself to 4 pages makes every word a valuable commodity). This is why we'll be asking those that plan to write adventures for SWL to give a sentence or two describing any magic items your adventure introduces. I'll be going through Hall of Bones, Grimmsgate and MCMLXXV in the next week or so to prepare cheat sheets to use them with SWL (mostly looking for magic items, spells and monsters that aren't in SWL) before moving on to Lost City of Barakus.