Dekar is the self-proclaimed strongest man in the world (which he actually is). He develops a rivalry with Guy, who is also determined to prove that he is the strongest warrior alive.
Although Dekar is very strong, he's very dumb and often falls into traps laid out for him, though his sheer brute strength always gets him out.
Dekar is a physical damage dealer with the ability to take large amounts of damage, similar to Guy, but Dekar has higher strength at the cost of lower speed.
There is much confusion to what weapon Dekar actually prefers. In Lufia II: Rise of the Sinistrals he is renowned for his fabled sword "Dekar Blade" (very useful IP, cuts a enemy's HP by 1/4), yet his in-game sprite depicts him holding a large axe, and axes can generally be only equipped by him.