Current problem with Arunafeltz Desert Sandwich:

Having 30 weight
Not tradeable / vending-able
NPC only accepting 2 Peaked Hats per dialogue -> Player only get 1x Sandwich per dialogue
NPC refuse to give out any Sandwich if player has 5x sandwich in inventory

If this is how official ragnarok actually works, I bet it's just one of their "grindy" stuff to make people buy Abrassive from Cash Shop instead of having to deal clicking the NPC, going to storage, clicking the NPC again, etc.

My suggestion would be:

Reduce the weight to 1
Make it tradeable / vending-able
Allow the player to turn in as many Peaked Hats as possible
Allow combining 3x Desert Sandwich to 1x 30min version of it
Maybe make it like Gemstone Refining UI to make it cleaner
Make the other 2 NPC (Hue, Ryosen) also do the same, so we can turn in stuffs easier

Potential good side from this:

Easier access to +7 CRIT food (10min) which is really neat for this server, cause we can't farm Buche de Noel
Easier access to other +5ATK/MATK and +10HIT/20FLEE food, probably less people would use this
Being consumables, this will enable the economy for newer players if the price of the Sandwich is being good in market. Cause I bet the high end players won't go down their way to Tatachos to farm the Sandwich themself, so they just buy from Market, while the newer players can farm it.

Potential bad side from this:

Giving an alternative to "Abrasive" probably will kinda reduce the amount of Abrasive being bought