Technique (TEC) is one of three offensive stats of a character. While it does not boost any kind of damage, it raises the possibility of hitting targets with a physical attack. Characters with good Technique are mostly archers, while most melee fighters have only mediocre or even bad Technique, making it harder to hit faster enemies. Its defensive counterpart is the Speed stat.
It should be noted that there are some skills that is always 100% success rates (not counting magic), no matter how low the Technique is. Boss characters tend to have this type of skill.