Ok, I'll give it a try (mostly to be corrected

):
Using your sword would mean "you" will need to throw a 10 or above on a D20 (Goblin has an armor class of 14 but since you have an attack bonus with your sword of +4 it's 10 (not sure how to handle "ties" so whether you have to roll a 11 or 10..)). By the description of your sword I'd say you deal 3 points of damage at minimum (2 by piercing and then one additional roll of a dice with six sides (D6). So basically between 3-8 points of damage. The goblin will most likely have about 8 hitpoints.
Using your spell Shocking Grasp would mean you still have to overcome the AC 14 of the goblin. I believe you have to accumulate the modifiers of intelligence (+3) and Proficiency (+2) and add to that one roll of a D20. So you'd basically have to roll a 9 or above to succeed. In case the Goblin wears an armor made out of metal you get an additional bonus but I don't know if the goblin does. Once succeeded, you would inflict 1-8 points of damage but also forcing the goblin to wait one turn (if I read that right).
I would do two things if I were you:
1) cast your spell since we all want to see some magic in action!! and
2) wait for a more experienced advise before doing 1).