It got even better for the Dragons after the break as Edinburgh missed numerous tackles and created little in the way of attacking play as the hosts took control.
Arlidge added another penalty, four minutes into the second half, and the pacy Harries collected two more tries before the hour mark to complete his hat-trick.
Gavin Thomas teed up his second as his pass gave Harries enough space to squeeze outside Mark Robertson and score.
The industrious Thomas provided the assist again, in the 56th minute, with his pass back inside sending the 23-year-old on his way to the try-line.
Edinburgh had a try ruled out by a push by winger Tim Visser and were now 21 points in arrears.
But, with some renewed vigour in the final quarter, they got themselves back in the game as centre Ben Cairns went under the posts, with Godman's conversion meaning they could draw with two more converted tries.
However, any revival was killed off completely when Dragons flyer Richard Fussell grabbed a sixth touchdown and full-back Martyn Thomas scored a spectacular 60-metre effort.
To their credit, Edinburgh fought to get something out of the match and managed it when Lions hooker Ross Ford came out of a pile of bodies with the ball to secure a bonus point for his side.
Edinburgh are now in fifth position, two points away from the play-off zone, with a home fixture against a struggling Ulster side next on th agenda.
Speaking after the reversal to the Dragons, Edinburgh coach Rob Moffat said: "You cannot defend like that - we gave away some really soft scores. You can't miss as many one-on-one tackles as we missed today and expect to win.
"Defensively we looked uncomfortable when they had the ball and, in fact, whichever team had the ball looked dangerous, so even when we trailed 28-14 in the second half I felt we'd still score another try or two.
"We're in the position we are in the league because we've lost our last two games and we've a lot of improving to do, especially in defence, for the Ulster game at Murrayfield next Sunday.
"But there's no point in feeling sorry for ourselves. We'll aim to rectify things for next Sunday."
|Newport Gwent Dragons Score Card|
|Edinburgh Rugby Score Card|