This will work on anything
I'm choosing the stun skill as an example
success rate is 80% / Skill max level is 11
Image is taken from Rev6 skill calculator >

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skill name is Daze skill code is SKILL_EU_WARLOCK_SOULA_STUN_A
How to find the skill code?
Extract the following text @Media\server_dep\silkroad\textdata\textdata_equip &skill.txt (or if you got that extracted already open it) and search for the skill name
*Note* The skill got 11 level so it will be like
SKILL_EU_WARLOCK_SOULA_STUN_A_01
SKILL_EU_WARLOCK_SOULA_STUN_A_02
and so on... (This skill got 11 so it end at _11)
Now that we got the skill code let's change the success % on the database
Code:
1 10978 699 SKILL_EU_WARLOCK_SOULA_STUN_A_01 ??:??? SKILL_EU_WARLOCK_SOULA_STUN_A 0 1 2 0 99999999 0 0 1166 10000 0 0 0 0 0 0 150 1 1 0 0 0 0 0 1 1 0 0 0 516 0 16 0 0 0 693 0 0 4 0 0 30 1 0 0 10 255 0 65 0 0 0 1 1 5 0 skill\europe\warlock_soula_stun_a.ddj SN_SKILL_EU_WARLOCK_SOULA_STUN_A xxx SN_SKILL_EU_WARLOCK_SOULA_STUN_A_TT_DESC SN_SKILL_EU_WARLOCK_SOULA_STUN_A_STUDY 0 69 0 29556 5000 80 2 1952542324 155 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1 10979 699 SKILL_EU_WARLOCK_SOULA_STUN_A_02 ??:??? SKILL_EU_WARLOCK_SOULA_STUN_A 0 2 2 0 99999999 0 0 1166 10000 0 0 0 0 0 0 150 1 1 0 0 0 0 0 1 1 0 0 0 516 0 26 0 0 0 693 0 0 6 0 0 108 1 0 0 10 255 0 119 0 0 0 1 1 5 0 skill\europe\warlock_soula_stun_a.ddj SN_SKILL_EU_WARLOCK_SOULA_STUN_A xxx SN_SKILL_EU_WARLOCK_SOULA_STUN_A_TT_DESC SN_SKILL_EU_WARLOCK_SOULA_STUN_A_STUDY 0 69 0 29556 5000 80 3 1952542324 271 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1 10980 699 SKILL_EU_WARLOCK_SOULA_STUN_A_03 ??:??? SKILL_EU_WARLOCK_SOULA_STUN_A 0 3 2 0 99999999 0 0 1166 10000 0 0 0 0 0 0 150 1 1 0 0 0 0 0 1 1 0 0 0 516 0 36 0 0 0 693 0 0 9 0 0 226 1 0 0 10 255 0 193 0 0 0 1 1 5 0 skill\europe\warlock_soula_stun_a.ddj SN_SKILL_EU_WARLOCK_SOULA_STUN_A xxx SN_SKILL_EU_WARLOCK_SOULA_STUN_A_TT_DESC SN_SKILL_EU_WARLOCK_SOULA_STUN_A_STUDY 0 69 0 29556 5000 80 4 1952542324 430 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1 10981 699 SKILL_EU_WARLOCK_SOULA_STUN_A_04 ??:??? SKILL_EU_WARLOCK_SOULA_STUN_A 0 4 2 0 99999999 0 0 1166 10000 0 0 0 0 0 0 150 1 1 0 0 0 0 0 1 1 0 0 0 516 0 46 0 0 0 693 0 0 11 0 0 393 1 0 0 10 255 0 295 0 0 0 1 1 5 0 skill\europe\warlock_soula_stun_a.ddj SN_SKILL_EU_WARLOCK_SOULA_STUN_A xxx SN_SKILL_EU_WARLOCK_SOULA_STUN_A_TT_DESC SN_SKILL_EU_WARLOCK_SOULA_STUN_A_STUDY 0 69 0 29556 5000 80 5 1952542324 646 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1 10982 699 SKILL_EU_WARLOCK_SOULA_STUN_A_05 ??:??? SKILL_EU_WARLOCK_SOULA_STUN_A 0 5 2 0 99999999 0 0 1166 10000 0 0 0 0 0 0 150 1 1 0 0 0 0 0 1 1 0 0 0 516 0 56 0 0 0 693 0 0 14 0 0 623 1 0 0 10 255 0 432 0 0 0 1 1 5 0 skill\europe\warlock_soula_stun_a.ddj SN_SKILL_EU_WARLOCK_SOULA_STUN_A xxx SN_SKILL_EU_WARLOCK_SOULA_STUN_A_TT_DESC SN_SKILL_EU_WARLOCK_SOULA_STUN_A_STUDY 0 69 0 29556 5000 80 6 1952542324 936 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1 10983 699 SKILL_EU_WARLOCK_SOULA_STUN_A_06 ??:??? SKILL_EU_WARLOCK_SOULA_STUN_A 0 6 2 0 99999999 0 0 1166 10000 0 0 0 0 0 0 150 1 1 0 0 0 0 0 1 1 0 0 0 516 0 66 0 0 0 693 0 0 16 0 0 1420 1 0 0 10 255 0 614 0 0 0 1 1 5 0 skill\europe\warlock_soula_stun_a.ddj SN_SKILL_EU_WARLOCK_SOULA_STUN_A xxx SN_SKILL_EU_WARLOCK_SOULA_STUN_A_TT_DESC SN_SKILL_EU_WARLOCK_SOULA_STUN_A_STUDY 0 69 0 29556 5000 80 7 1952542324 1322 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1 10984 699 SKILL_EU_WARLOCK_SOULA_STUN_A_07 ??:??? SKILL_EU_WARLOCK_SOULA_STUN_A 0 7 2 0 99999999 0 0 1166 10000 0 0 0 0 0 0 150 1 1 0 0 0 0 0 1 1 0 0 0 516 0 76 0 0 0 693 0 0 19 0 0 2164 1 0 0 10 255 0 856 0 0 0 1 1 5 0 skill\europe\warlock_soula_stun_a.ddj SN_SKILL_EU_WARLOCK_SOULA_STUN_A xxx SN_SKILL_EU_WARLOCK_SOULA_STUN_A_TT_DESC SN_SKILL_EU_WARLOCK_SOULA_STUN_A_STUDY 0 69 0 29556 5000 80 8 1952542324 1833 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1 10985 699 SKILL_EU_WARLOCK_SOULA_STUN_A_08 ??:??? SKILL_EU_WARLOCK_SOULA_STUN_A 0 8 2 0 99999999 0 0 1166 10000 0 0 0 0 0 0 150 1 1 0 0 0 0 0 1 1 0 0 0 516 0 86 0 0 0 693 0 0 21 0 0 4689 1 0 0 10 255 0 1174 0 0 0 1 1 5 0 skill\europe\warlock_soula_stun_a.ddj SN_SKILL_EU_WARLOCK_SOULA_STUN_A xxx SN_SKILL_EU_WARLOCK_SOULA_STUN_A_TT_DESC SN_SKILL_EU_WARLOCK_SOULA_STUN_A_STUDY 0 69 0 29556 5000 80 9 1952542324 2503 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1 10986 699 SKILL_EU_WARLOCK_SOULA_STUN_A_09 ??:??? SKILL_EU_WARLOCK_SOULA_STUN_A 0 9 2 0 99999999 0 0 1166 10000 0 0 0 0 0 0 150 1 1 0 0 0 0 0 1 1 0 0 0 516 0 96 0 0 0 693 0 0 24 0 0 9013 1 0 0 10 255 0 1590 0 0 0 1 1 5 0 skill\europe\warlock_soula_stun_a.ddj SN_SKILL_EU_WARLOCK_SOULA_STUN_A xxx SN_SKILL_EU_WARLOCK_SOULA_STUN_A_TT_DESC SN_SKILL_EU_WARLOCK_SOULA_STUN_A_STUDY 0 69 0 29556 5000 80 10 1952542324 3379 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1 10987 699 SKILL_EU_WARLOCK_SOULA_STUN_A_10 ??:??? SKILL_EU_WARLOCK_SOULA_STUN_A 0 10 2 0 99999999 0 0 1166 10000 0 0 0 0 0 0 150 1 1 0 0 0 0 0 1 1 0 0 0 516 0 106 0 0 0 693 0 0 26 0 0 16418 1 0 0 10 255 0 2132 0 0 0 1 1 5 0 skill\europe\warlock_soula_stun_a.ddj SN_SKILL_EU_WARLOCK_SOULA_STUN_A xxx SN_SKILL_EU_WARLOCK_SOULA_STUN_A_TT_DESC SN_SKILL_EU_WARLOCK_SOULA_STUN_A_STUDY 0 69 0 29556 5000 80 11 1952542324 4519 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 10988 699 SKILL_EU_WARLOCK_SOULA_STUN_A_11 ??:??? SKILL_EU_WARLOCK_SOULA_STUN_A 0 11 2 0 99999999 0 0 1166 10000 0 0 0 0 0 0 150 1 1 0 0 0 0 0 1 1 0 0 0 516 0 116 0 0 0 693 0 0 29 0 0 23138 1 0 0 10 255 0 2836 0 0 0 1 1 5 0 skill\europe\warlock_soula_stun_a.ddj SN_SKILL_EU_WARLOCK_SOULA_STUN_A xxx SN_SKILL_EU_WARLOCK_SOULA_STUN_A_TT_DESC SN_SKILL_EU_WARLOCK_SOULA_STUN_A_STUDY 0 69 0 29556 5000 80 12 1952542324 5996 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
follow the line until you find 80 (which is the success rate)
and change it to w/e you want
You can do this DB side only but in order the change to take effect you need to do the media side as well in skilldata%enc.txt