Heat grill on medium-high.
Cook sausages for 10 minutes, making sure to turn to prevent burning. Season fennel with salt and pepper, brush with olive oil, and grill until brown and tender, about 20 minutes. When cool enough to handle, slice the sausages on the bias into 1/4-inch slices, and cut the fennel into similarly sized pieces. Keep the sausage and fennel warm until ready to use.
Bring a large pot of salted water to a boil for the pasta. Cook the pasta al dente.
In another large pot of water, add lemon, onion, salt, and pepper and bring to a boil. Add trimmed artichokes and top with a small plate to weight down artichokes. Cook until hearts are almost tender, about 15 minutes. Remove from pot and pat dry. Season with salt and pepper, and place on grill to cook for 5 minutes. When cool enough to handle, halve the artichokes.
In a medium sized bowl, mix the vinegar and mustard. Slowly whisk in oil until emulsified. Mix in salt, sugar, and pepper. Toss the sausage, fennel, artichokes, and pasta with walnut vinaigrette and plate, garnishing with the whole parsley leaves. Serve immediately.