I wouldn't suggest a melee guardian. Their base dex is terrible, and their starting stat points are much more conducive to a healer or hybrid because of the huge intelligence.
But, however, if you really want to, I'd suggest EE clubs, and then dexterity on your armour and charm. Clubs are basically your only choice for weapons because they're the only non-heavy weapon that guardians can use, and I wouldn't recommend the heavy weapon route unless you've got lots of fg to dump on it.
If you want to use a guardian to their full capacity I would make a healer. Go for HM gear and EE on your heal charm and dump every stat point into intelligence and you'll be good. And if you really want to melee then I would highly recommend using a fighter instead of a guardian
just my opinion though