ZillaPrime said:

That sounds very sensible. I didn't realise other NPCs had it as well. I wonder where they were going with that...

Actually, the Athletics skill is mentioned in the DH Core Rulebook…Daemonettes have it as a skill

I started hunting down the Athletics skill when I was generating a Xenos race using the procedure in the GM's Screen booklet and it assigned the Athletics skill to my new species.  Never did find it until…the Athletics skill was included in Black Crusade…

ATHLETICS (STRENGTH)

Athletics is the ability to run long distances, climb sheer surfaces ,and swim strongly without tiring or faltering. It encompasses all manner of strength and brawn based tasks that a character may undertake; a skilled athlete can run for miles, heft mighty loads, or cross fast-flowing rivers with relative ease. Athletics also allows a character to push themselves to greater levels of endurance and shrug off the effects of fatigue when running, swimming, or climbing.

The GM may call on players to use the Athletics Skill when:
• They must swim across a body of water or try to stay afloat.
• They wish to push themselves beyond their limits and keep going even when exhausted.
• They want to climb a cliff or cross extremely rough ground.

A character’s background may dispose him more towards certain types of athletics. Not all skilled climbers make excellent swimmers, though both may have similar upper body strength. A GM can keep this in mind when determining the difficulty of a Test. For example, a character from a desert world or a Heretek with extensive augmentic parts could be required to make more difficult Athletics Tests to swim across a river than a character who grew up on an aquatic hive world.

EXAMPLE MODIFIERS

+30 - Climbing a ladder in a hurry or swimming in perfectly calm water.
+20 - Climbing across a gantry or swimming with some method of staying afloat.
+10 - Climbing the outside of a hive or swimming with specialized gear (i.e. flippers).
+0 - Climbing a rough rock wall with protruding stones, or swimming across a deep lake.
–10 - Climbing a brick wall or swimming a slow river.
–20 - Climbing a ferrocrete wall without climbing aids or swimming against a current.
–30 - Climbing up a slick plasteel bulkhead or swimming in a storm.

Skill Use: Full Action unless otherwise noted.

Oh, I missed this little blurb from the next page…

SPECIAL USES FOR ATHLETICS

The following are special uses for the Athletics Skill.

ENDURANCE

Trained athletes are extremely fit and can push themselves far beyond the ability of normal people.  As a Free Action, a character with the Athletics Skill may make an Athletics Skill Test at –10 whenever they suffer a level of Fatigue as a result of running, swimming, or climbing to ignore its effects.  The character may continue to take tests and ignore Fatigue gained in this way indefinitely; however as soon as he fails a test he must rest for at least 4 hours and cannot use his Athletics Skill again during that time.

HEFT

Athletes are also known for their strength and can lift great weights for short periods of time.  As a Free Action, a character may make an Athletics Skill Test to increase their carrying capability for a single Encounter.  For every Degree of Success the character achieves, his Strength is increased by 10 for the purposes of how much weight they can carry, lift, or drag to a maximum of modified Strength of 100.  Hefting may only be attempted once, and if the character fails the test he may not try again until the next Encounter.

Yeah, that sounds about right, combining several skills that see minimal trained use into one better skill. Of course, in BC, raising skills costs more, so I suppose it balances out.

In perusing the beta version of Only War, I can see that the Athletics skill is in that system too (verbatim to the text from Black Crusade).