Bombs tend to be of the support type, and not very big on damage. You have an elemental weapon, but you lack piercing and shadow. For piercing, you have the choice of flourish/snarby sword for swords, snarby bomb for bombs, and the callahan or blitz for piercing guns. I would say to get the piercing bomb from the snarbolax token rewards if you want a bomb. Otherwise, go for a flourish or the sword from the same token source. Flourish is cheaper to obtain than the snarby sword, if money is a factor in your decision making process.

For shadow swords, you have a choice of acheron and gran faust. Acheron is another line of the brandish family, 3 hits and a line of explosion for the charge attack. Guns, you can choose between umbra, sentenza, and biohazard. Of the 3, umbra is quite possibly the cheapest to get, since the recipes are available at Hall of Heroes. The other 2 are boss rewards, antigua and catalyzer respectively. Those require tokens from RJP or IMF, depending on your style if you were to gun. Sentenza is your basic 6 shooter. Fast shots, low damage each. But they do great for single target dps. Catalyzer line is more of a sticky bomb/mass explosion type of weapon. Charged shots will circle enemies and normal shots will proc those charged orbs, creating an explosion. Multiple shots can be loaded onto an enemy. For shadow bombs, you can only choose between graviton and dark retribution. Graviton is a vortex styled bomb. Gathers enemies, then explodes, dealing damage and flinging all enemies caught in the vortex back. Dark retribution is a bomb that lays down circling orbs in a zone. Each orb does damage every time it comes in contact with an enemy. It does require you to pay for unlockable content in order to receive.

If you still wish to start building a bomb to use and ignore damage types, try making one of several haze bombs. The haze bombs cover an area, increasing with upgrades, with a status effect. Any enemy inside such a haze will constantly receive the status infliction until leaving the zone or when the haze dissipates. Fire, freeze, poison, and shock are all useful statuses to lay upon an enemy before wailing on with another weapon. Shock requires boss tokens from IMF to obtain. Another possible utility bomb is the vortex line. I personally prefer the electron vortex over the graviton. The Ev applies shock on explosion, which keeps enemies grouped up most of the time. Graviton will gather enemies just as well, but fling them over a large area.

To make the most of your armor, I would say get a piercing sword to take advantage of the damage bonus. Piercing swords tend to deal with pierce-weak enemies easier than most other weapons. Other piercing weapons sacrifice either damage for survivability or vice versa. A well trained pierce sword deals enough damage to kill while maintaining a degree of safety.