How can I make players spawn with a sword after dying?
You need a death Counter first
/scoreboard objectives add deaths deathCount
I recommend functions but you can use a repeat command block and a chain command block, too
/execute as @a[scores={deaths=1..}] run give @s minecraft:iron_sword
/execute as @a[scores={deaths=1..}] run scoreboard players reset @s deaths
Use a scoreboard objective that tracks the time since the player last died.
/scoreboard players add deathTime time_since_death
Then run, in a repeating command block:
/give @a[scores={deathTime=1}] wooden_sword