Whel all about rune gain/lvl is in scripts/logic_hero.lua file , check it out and you`ll find 3 strings with description of rune/lvl i`m not sure which you want to remove original settings or this that grimeleven added in RSE mod.
As for poison dmg, iguess you thinking about +3dmg from royal snake ring. Go to sessions/red sands/config/items.txt and find royal_snake_ring and add there snake_celestial to string containing rest of snakes.
Also in same file find snake_boots and add celestial snakes to +1speed/inititative for them for that item.
Good luck
Found this miss ppl, add in sessions/config/items.txt snake_celestial to snake boots and royal snake ring to bonuses for +1initiative/speed (boots) and +3poison dmg in ring
In sessions/config/companions.txt for glavk add snake_celestial for +5defense , +1moral.
Question : how to add bonus resistances form lvlup units to astral res. Guardian medal gives astral res to units, but not lvl`s when units lvlup in battles. I see physical/fire/magic/poison res when unit get new lvl with +res bonus, but not astral. Where to change this setting ?