The arrows only weigh 0.1 or 0.2, and they go in the ETC tab so they won't take up berry slots. I'm sure people don't use EVERY element there is, mostly Ghost, an x element for people without GR, and maybe holy and shadow. Arrows also aren't the only offensive skill that clowns/gypsises have. Maybe I might be seeing things, but I always see a clown/gypsy spamming tarot when their AV spam doesn't kill their target. Also, most of the skills used only consume 1 arrow per skill use. Seeing as how the arrows only weigh 0.1 or 0.2, 4000 oridecon arrows would weigh 800, the weight of a STR belt. Seeing as how gypsies and stalkers have(or can have) offensive skills that don't require arrows, the only one left is sniper; however I recall Snipers' Soaring Bird has a weight limit increase so they should be able to carry multiple arrows.