Spec'ing for fire criticals is currently the best way to boost the damage of arti nukes (tac det, prismatic) [due to superior lore being available on an easily wearable item]. Whilst both spells are used primarily as cc by most artificers, they both have excellent base damage - prismatic is 30d6, whilst Tac Det is 20d2+20 [force] + 10d3 + 30 [fire], or 70 force + 50 fire on average. This makes prismatic a top end single-target nuke and tac det one of the best AoEs short of meteor swarm, or a 25th level DBF. The problem with both spells is the expensive base sp cost, and the fact that artis can't effectively lower their empower or maximise costs.
However, if you're spec'ing fire anyway for the runearm say, then you'd end up with a very damaging emergency nuke if you so wanted.