Regarding critical damage with the revamp

Sounds plausible. Level up. Take screen shots for each AP you add. See what happens.

Not related to my slinger, but I did this for my magician earlier.

 Level 17

 Level 18, +1 LUK

 Level 18, +1 LUK, +1 INT

 Level 18, +1 LUK, +2 INT

 Level 18, +1 LUK, +3 INT

 Level 18, +1 LUK, +4 INT

 And some random, somewhat unorganized data

Level 16
(69INT, 18LUK, 55MATK)
36~142
+1 LUK
36~143
+1 INT
36~145
+1 INT
37~147
+1 INT
37~149
+1 INT
38~151
(74INT, 19LUK, 55MATK)

31~123
+10 MATK
38~151
7~28

Level 17
(74INT, 19LUK, 55MATK)
38~151
+1 LUK
38~151
+1 INT
38~153
+1 INT
39~155
+1 INT
39~157
+1 INT
40~159
(79int, 20luk, 55matk)

33~130
+10 MATK
40~159
7~29

Level 18
40~159
+1 LUK
40~159
+1 INT
40~161
+1 INT
41~163
+1 INT
41~165
+1 INT
41~167

34~137
+10 MATK
41~167
7~30

The range before the +10 MATK thing is from removing one of my pet equips that give +10 MATK, the range after is after putting it back on.