Today's your lucky day! Both those can be fixed without regenerating your world, you basically just need to go into your raws and change the values, good luck with teh farming, i'm doing this myself and ended up getting in over my head as i'm now attempting a total overhaul of aboveground crops including edibility of unprocessed seeds, brewing AFTER milling, etc...
Ill probably never finish.
So anyway, to fix Whips ( you should fix scourges and large daggers too since they're also rather excessively pointy.
From your df folder go into data/save/ then into whichever folder your save is actually in , then into raw/objects .. then open item_weapon, find whips (top entry) change the line
[ATTACK:BLUNT:1:10:lash:lashes:NO_SUB:5000]
the first number after Blunt is contact area, make it much larger to stop whips being lightsabers, axes have 100, try 20 or something (you could change the raws in the main folder and test in arena)
FOr plants look in the file Plant_standard , the file has a good description of everything above the first entry. You'll see
[SPRING][SUMMER][AUTUMN][WINTER] in all the ones you want to mod, just delete the inappropiate ones, also i'll suggest adding [GROWDUR:
] or whatever to the plants to change their growth time, all above ground plants seem to take 42 days (which is equilivent to growdur 500.) Eact day of growth requires a growdur of 12, so for a 90 day crop add [GROWDUR:1080]
Most cereal crops in reality take about 100 days, Root vegetables can take 30 days, some plants take 2 years (pineapple, asparagus) I think you can actually have plants take multiple years as long as you make them able to grow in all seasons.
Edit: I think i once changed whips to a value that made them easily break bones and cause bleeding against unarmoured areas but were generally unable to get past even copper armour. That seemed good enough to me.