I hate to keep using Artos_Fabril's ideas whenever this comes up but he did make some GREAT suggestions (using the currently proposed new system)
Code:
Mechanic
Enhancement Name Cost Progression Class Level Requirement Benefit
Engineering 1/1/1/1 3/6/9/12 +1 to Disable Device, Open Lock, Search, Spot
->Reverse Engineering 1/1/1 6/10/14 +1 to Use Magic Device, +1 crafting level, +2 trap DC
Combat Engineer 1/1/1/1/1/1/1 1/3/5/7/9/11/13 1 use per tier of "Combat Engineer"**
->Demolitionist 1/1/1 9/11/13 While Combat Engineer is active, your traps are emplaced instantly; traps and grenades have a 4% chance per tier to crit for double damage
->->Big Ba-da-boom 3 15 Consume a use of "Combat Engineer" to increase all trap, grenade, and crossbow damage by 50% for 8 seconds
->->->Mass Destruction 1 18 When your score a kill with a grenade, reclaim one use of "Combat Engineer"
Bolt-Ridden 1/1/1/1/1 2/6/10/14/18 Repeater criticals reduce enemy fortification by 2% and fortitude saves by 1 for 10 seconds, 1 stack per tier
Mechanical Aptitude 1/1/1/1/1 4/7/10/13/16 Increase the enhancement bonus of your repeating crossbow by 1 per tier
->Repeater Specialization 1/1/1 8/12/16 +2 damage per tier with your equipped repeater
->->Repeating Repeater 1/1/1/1/1 6/9/12/15/18 Your repeater has a 1% chance per tier to fire a second volley immediately
->->->Repeater Mastery 2/2 15/18 Reduce repeater reload time by 25% per tier (multiplicative stacking with rapid reload)
->->->->Sabot Shots 2 18 +1 to Critical multiplier on vorpal strikes with all crossbows/repeaters
Manual Dexterity 1/1/1/1/1 3/6/9/12/15 Reduces time to open lock or disarm by 20% per tier
->Nimble Mind 3 12 Add your dex bonus to your disable device total
Practiced Eye 1/1/1/1/1 1/3/5/7/9 +1 spot and -20% search time per tier
Monkeywrencher 1/1/1/1 3/8/13/18 +1d6 per tier bane damage to constructs
->Wrack Construct 1/1/1 5/10/15 Wrack Construct I/II/III (as current)
->->Ruin Construct 2 12 Wrack construct stuns on crits; red/purple named lose additional 15% fort instead
Repair Construct 1/1/1/1 1/4/7/10 repair 1d3+3 per second, per tier - 15 second duration
Trap Resistance 1/1/1 2/8/14 +2 to saves vs. traps and +3 to all elemental resistances per tier
**Combat Engineer: Traps take 50% less time to place and enemies who successfully save still have their defenses compromised, reducing fortification by 10% for 10 seconds (does not stack with itself)
Granted Benefits
Tier .5 Light Repeating Crossbow Proficiency; Critical fail while disarming trap dazes you, but does not explode the box
Tier 1 Add your Int bonus to crossbow/repeater damage; your trap DCs are increased; all of your traps and grenades deal 10% more damage
Tier 1.5 Heavy Repeating Crossbow Proficiency; +3 to Disable Device, Open Locks, and Search
Tier 2 Add half your dex bonus to sneak attack damage; your trap DCs are increased; +3% crit chance with traps and grenades (+0.5 multiplier)
Tier 2.5 Smite constructs/living constructs; +3 to elemental resistances, 10% damage reduction vs physical traps
Tier 3 Great Crossbow Proficientcy; your trap DCs are increased; traps and grenades deal addional 15% damage
Capstone: +2 Int; All light/heavy/great crossbows you wield fire volleys of 3 bolts, instead of 1; Trap DCs increased