this sort of parallel i think is perfect, you don't need items for every spell out there but there's certain basic effects that martials can barely even attempt to replicate, pick out a list of the core essential spell effects that really divide the line and write up some gear that replicates spell effects in the same 'stamina over potency' design of martials,
a caster has 20ft cube of web, a martial has a 15ft square of fixed DC throwable tanglenet that can be retrieved after battle,
a caster has comprehend languages, a martial has a book of translation indexes they can use with INT checks,
a caster has remove curse, a martial has purification powder that they can make an arcana or religion check with.