Guild Wars 2

Bombs and grenades work well with condition builds, so rabid and dire are both fine.

For PvE, power grenadier is the meta. However, you don’t want Fire and Air sigils there, just get Force and Night/[Whatever] Slaying.

In WvW, almost anything can work. For example, I often roam with a full berserker Static Discharge build, which also happens to be one of the most fun engineer builds I’ve played. I’m sure you could put together a decent power grenadier build (though, again, Air+Fire might not be the most optimal sigil choice).

For PvP, you’d be better off on something slightly tankier. If you take the celestial amulet, you’d do nearly the same damage as a berserker (don’t forget that grenades also pack a significant amount of conditions), while having significantly more sustain. In the recent meta, you’re either a bunker (with celestial to do damage), a thief or dead.

Air and Fire sigils are most useful on power (especially berserker) builds for additional burst every few seconds, letting you attack intermittently as you kite while still doing good damage. If you’re running a power grenadier build, then sure, they will work just fine, though you should also consider taking other sigils, such as Battle or Force.

On a celestial or condition build, you’d be better off taking different sigils, such as Battle, Doom, Geomancy or Earth for offensive sigils and Generosity (PvP) or Cleansing (WvW) to handle conditions.

A bit strange to see the celestial amulet on a pistol/shield bomb build; the only real source of power damage in there is the bomb autoattack. In my opinion, the rabid amulet would greatly increase your damage and overall effectiveness.

Additionally, Cloaking Device is a weird trait to take in PvP, since it will only make you lose the point you’re holding. I doubt that anyone will really fall for an engineer suddenly disappearing just as they land an immobilize, so you should expect them to just continue attacking the spot where you’re standing. If you drop it, you can put two points into Alchemy for Protection Injection or Explosives for Short Fuse (or even drop Hair Trigger and take both).