Frickin’ Laser Beams: Invisible. Recoilless. Travel at the speed of light. In short, just like actual frickin’ laser beams.
(See Energy Weapons and Kinetic Weapons Are Just Better for where they are used, and why they’re not usually considered the primary weapon set in the Eldraeverse, which I didn’t particularly feel like repeating right here.)
As a side note of things mentioned elsewhere on the defensive side, the chief purpose of lasers as ship-to-ship weapons is for pumping heat into the enemy. The defense against this is twofold: one, thermal superconductor (or, previously to the invention of this particular piece of exotic material, mere thermal-very-good-conductor-convector-etc.) plating to avoid localized hot spots heating up and exploding, and lots of goo of very high thermal heat capacity to dump heat into and then pump overboard. This doesn’t stop you from eventually having to heave to, extend your radiators, and quit the fight, but it does slow down getting to that point rather a lot. Similar plating to the former used in personal armor makes personal laser-arms, while not unuseful on the battlefield, certainly not the most useful thing which you can carry.
tl;dr They have their place in combat, but they’re not magically supreme on the field, and indeed are unlikely to be your primary weapons.
Also, while it would certainly be technologically possible to attach them to cyborg sharks, so far as I know, it’s never actually been done.