Dorudugan is immune to Interrupt. So if you plan to fight it, you should have some backup plans.
Even if you don't plan on doing megabosses, seemingly like half the boss fights in FS are against an interrupt-immune target.
You'd also want to stay away from Galawain's Challenge become Unstoppable would also make them interrupt-immune and there's a 1/6 chance that Exalted would give them interrupt immunity (via Courageous).
Re: weapon: I would recommend Saru-Sichr, even if it's not as much "in theme", because chance of paralyze per tick of damage is even better than a weak effect on an interrupt. Beyond that, just stick with morning stars, since the -25 fort debuff + brute force = lots of crits.
an alternate choice is to get the Slayer's Claw from SSS (upgrades might inspirations a tier) and roll either a berserker (their tenacious frenzy becomes energized) or a monk (their thundering blows will grant energized); energized will do the same thing as Interrupting Blows does (50% chance to interrupt on crit). might be hard to get easily on solo though.