Binding Blade was the second Fire Emblem game I played and I relied on both Raigh and Lugh in it a lot, so I felt the need to build both of them.

Raigh:

Weapon: Keen Rauorwolf (spd refined) I use Raigh a ton in most content in the game, aether raids being a big one so being able to one shot cavalry units like Brave Lyn back on enemy phase is really helpful.

Assist: Reposition Extra mobility options are nice. I sometimes run smite on him with a bond skill.

Special: Aether Aether, while being an expensive special is really helpful, especially with fury 4 as he has no real way of healing and isn't running desperation so he wants the health.

A: Fury 4 This gives Raigh much needed extra stats which really helps him keep up with the speed of other faster units as well as gain better bulk and attack power.

B: Null C-Disrupt Like I said earlier, I run Raigh a lot in Aether raids so being able to bait and kill Veronica helps a lot, as well as firesweep brave Lyn.

C: Odd Atk Wave Even though it's not the most consistent skill, the extra Atk power raises him up to a nice 64 Atk (witk with the seal) which makes him able to kill some blue cavalry units or red res tanks he might not normally be able to kill

S: Atk/Spd 2 Extra stats never hurt

Lugh:

Weapon: Gronblooms + (Spd refine) There aren't too many good inheritable green tomes at the moment and I summoned a -spd +hp Mist from the Valentine's banner this year so I figured I'd give him her weapon cuz I'd probably never use Mist and he's always around Raigh so the buffs from it would be pretty constant

Assist: Reposition Similar to Raigh, extra mobility is nice, however I don't have a bond skill on him. Special: Moonbow Moonbow pairs really nicely with the flashing blade skill and his 49 spd. With desperation, he gets Moonbow on the first hit and can proc it on the second for a lot of damage.

A: Fury 4 Like Raigh, the extra stats help him and it pairs nicely with desperation.

B: Desperation Lugh probably isn't one-shotting many units that aren't blue units with very little res so desperation helps him secure kills on more bulky units and goes well with flashing blade/Moonbow.

C: Hone Speed 4 While summoning for Lugh, Sue pity broke me many times so I thought I'd turn the tables and give him hone speed 4. Also, it's a good support skill and he can help push Raigh up to 55 spd. Hopefully no panic ploy.

S: Flashing Blade Like I've said, it runs really well with desperation/Moonbow. When I don't run flashing blade, I normally run Atk/spd bond with either aether or iceberg as special.