Skill_unit_db.txt is use for layout of ground type skilll..
if you wish only eske skill will work on players..edit your skill.c an recompile
case SL_SKA: // [marquis007]
-case SL_SKE:
if (sd && !battle_config.allow_es_magic_pc && bl->type != BL_MOB) {
clif_skill_fail(sd,skillid,USESKILL_FAIL_LEVEL,0);
status_change_start(src,SC_STUN,10000,skilllv,0,0,0,500,10);
break;
}
+case SL_SKE:
clif_skill_nodamage(src,bl,skillid,skilllv,sc_start(bl,type,100,skilllv,skill_get_time(skillid,skilllv)));
if (skillid == SL_SKE)
sc_start(src,SC_SMA,100,skilllv,skill_get_time(SL_SMA,skilllv));
break;