STR/DEX is the best way to maximize your damage output IMO.
Looking at the stats without any weapon factoring into it… we can calculate damages based on your raw attack power.
Level 100 Rank 4 Swordsman
P.ATK - 175
CRIT.ATK - 75
CRIT.RATE - 75
Total damage: (P.ATK * 1.5 [CRIT.RATE] + CRIT.ATK)
= 337.5 DMG w/ CRIT
P.ATK - 269
CRIT.ATK - 169
CRIT.RATE - 6 (0% chance of crit)
= 269 DMG w/o CRIT
P.ATK - 110
CRIT.ATK - 10
CRIT.RATE - 127
Total damage: (P.ATK * 1.5 [CRIT.RATE] + CRIT.ATK)
= 175 DMG w/ CRIT
As you can see, going pure STR has the highest consistent damage. DEX yields the lowest damage output. Even if you crit, you are doing less damage than a full STR build. A hybrid of STR and DEX yields more potential damage.
Now that isn’t to say DEX builds are bad. They definitely scale better with classes that have high damage dealing skills, but your basic attack damage will be utter crap compared to a STR build. A STR build has very high basic attack damage, but their skills are likely never going to crit.
If you’re a class that relies a lot on skills, DEX is a good build. You give up basic attack damage for skill damage.
If you’re a class that does a lot of basic attacking, STR is better for you. This tends to fall under tank classes or classes with limited move sets or high cooldowns.
Weapons factor into this mix quite a bit so it can make either build better depending on the type of equips you use.
There’s really no wrong way about going with what you’re doing, just realize that the build you’re doing has different results depending on the type of class you choose.
A full DEX Peltasta for an example is probably not the best build you could do. The safest builds to do are STR builds. DEX is good, but too much of it while sacrificing attack is a bit pointless unless you have equips that boost CRIT.ATK very high. Even then, CRIT.ATK is just an addition to your damage formula in the same sense how concentrate and blessing work. That extra 75 DMG added onto the end of your attack doesn’t affect too much if your skills are hitting over 2k of damage. Because there isn’t much of a difference between a skill hitting 2,000 damage and 2,075 damage. If you can somehow balance high CRIT.ATK with DEX… that would likely be the ultimate build.