I still keep Ungur's Boomerang handy. It's good for soloing, although I've generally never used it inside of Abyssea due to how awesome Qirmiz Tathlum becomes in there.

In regards to difference weaponskill bonuses and the like~

Any weaponskill that can crit has some kind of bonus to the critical hit rate based on TP. Something like +10%/+30%/+50% critical hit rate on 100/200/300 TP would be an example of what I mean. This will be added onto your base critical hit rate, which is determined by dDEX (capping out at +20% critical hit rate when you have 50 more DEX than the mob's AGI), merits (+4%), and misc. pieces of gear. Each weaponskill can be different and there are exceptions. True Strike, for example, has a 100% critical hit rate and the accuracy of the WS varies with TP. I remember reading a general rule of thumb I remember coming across on Studio Gobli for most crit modified weaponskills, but I can't remember what it was and I don't remember where I found it...

Either way, base critical hit rate is going to be much lower outside of Abyssea so pieces like Loki's Kaftan take a huge hit. The damage increase a weaponskill receives is still on par with a normal hit (pDIF +1.) At it's worst (when your cRatio is maxed), a crit will increase your overall damage by around 40%~ or so. So it's definitely nice to have, although without an precise understand of how Blade: Hi's critical hit rate changes with TP, it will be difficult to actually quantify the benefit of a lot of gear.

As far as accuracy goes, all weaponskills receive an accuracy bonus to their first hit. That was the reasoning behind the general rule of thumb about not worrying about accuracy for single hit weaponskills as much as multihit. However, no weaponskill is going to benefit from having more accuracy than is needed to achieve 95% melee accuracy. This occurs easily on non Abyssea mobs without trying for it, so I don't even consider it.

There's no rule as far as attack vs secondary mods go. This idea was popularized by MNKs because the secondary mods are low for Asuran Fists (10% STR 10% VIT.) In their case, there was very little benefit to stacking those attributes while attack would still provide a steady increase in damage (like it does for every other weaponskill.) However, each weaponskill is different. Victory Smite, for instance, has a 60% STR mod. There is a huge gain in stacking STR for that. There's going to be a balance that's changes for each weaponskill and situation that would determine what is better.