The patch does the following to the following NPCs:

Penitus Oculatus Agents;
 - Will now spawn with Imperial Crossbows instead of bows, 50% chance to spawn with Imperial Bolts, 50% chance to spawn with elemental Imperial Bolts
// Same behavior as in my other mod, DX Faction Crossbows - Leveled Lists Addon. They're assassins, not battlefield soldiers - imo it makes sense for them have crossbows since they're not as clunky as bows in close quarters

Rogue Penitus Oculatus Agents (radiant quest);
  - Have a 25% chance of spawning with a Imperial Crossbow instead of a leveled bow, 50% chance to spawn with Imperial Bolts, 50% chance to spawn with elemental Imperial Bolts

Dawnstar Sanctuary Brotherhood Assassins;
 - One of the assassins will now spawn with a Dark Brotherhood Crossbow and a mixture of elemental Brotherhood Bolts instead of a Ebony Bow and -Arrows
// The others either don't have ranged weapons to begin with or use a unique ranged weapon so they remain as they are

Remnant Dark Brotherhood Assassins (radiant quest);
 - Have a 25% chance of spawning with a Brotherhood Crossbow and -Bolts instead of a leveled bow and arrows.



Thoughts on balancing;
Please be aware these crossbows pack a major punch, they ignore 50% of armor, have higher damage values and therefore might upset the balancing a bit. The Brotherhood Crossbow, for example, is one of the strongest ranged weapons that can be found in the game - depending on the mods you have enabled that change the difficulty like Wildcat or KYE you might not have a good time when fighting an enemy which uses these types of crossbows. You might therefore want to check out the optional balance patch here which lowers the strength of the Imperial Crossbow.

Note: The Patch doesn't contain any assets of the original mods, it is therefore not standalone!



Compatibility;
 - Technically not compatible with other mods that change the same NPCs. The patch doesn't touch any existing leveled lists or items so it should be compatible with pretty much everything, including the leveled lists addon for Faction Crossbows mentioned above



Credits (don't forget to endorse these!);
 - https://www.nexusmods.com/skyrimspecialedition/mods/4047, Deserter X for the wonderful mod 'DX Faction Crossbows'
 - https://www.nexusmods.com/skyrimspecialedition/mods/21061, wankingSkeever for the equally amazing mod 'Penitus Oculatus'
 - https://www.nexusmods.com/skyrimspecialedition/mods/164, the xEdit team for creating SSEEdit